diff --git a/packages/@react-aria/tabs/src/useTabPanel.ts b/packages/@react-aria/tabs/src/useTabPanel.ts
index 42e9825006d..fb2c42cce0e 100644
--- a/packages/@react-aria/tabs/src/useTabPanel.ts
+++ b/packages/@react-aria/tabs/src/useTabPanel.ts
@@ -27,7 +27,7 @@ export interface TabPanelAria {
  * Provides the behavior and accessibility implementation for a tab panel. A tab panel is a container for
  * the contents of a tab, and is shown when the tab is selected.
  */
-export function useTabPanel<T>(props: AriaTabPanelProps, state: TabListState<T>, ref: RefObject<Element | null>): TabPanelAria {
+export function useTabPanel<T>(props: AriaTabPanelProps, state: TabListState<T> | null, ref: RefObject<Element | null>): TabPanelAria {
   // The tabpanel should have tabIndex=0 when there are no tabbable elements within it.
   // Otherwise, tabbing from the focused tab should go directly to the first tabbable element
   // within the tabpanel.
diff --git a/packages/@react-aria/tabs/src/utils.ts b/packages/@react-aria/tabs/src/utils.ts
index 8311be6f686..7f7d01b92d4 100644
--- a/packages/@react-aria/tabs/src/utils.ts
+++ b/packages/@react-aria/tabs/src/utils.ts
@@ -15,7 +15,11 @@ import {TabListState} from '@react-stately/tabs';
 
 export const tabsIds = new WeakMap<TabListState<unknown>, string>();
 
-export function generateId<T>(state: TabListState<T>, key: Key, role: string) {
+export function generateId<T>(state: TabListState<T> | null, key: Key | null | undefined, role: string) {
+  if (!state) {
+    // this case should only happen in the first render before the tabs are registered
+    return '';
+  }
   if (typeof key === 'string') {
     key = key.replace(/\s+/g, '');
   }
diff --git a/packages/@react-spectrum/autocomplete/src/SearchAutocomplete.tsx b/packages/@react-spectrum/autocomplete/src/SearchAutocomplete.tsx
index ad0af675c72..3b97d0286ea 100644
--- a/packages/@react-spectrum/autocomplete/src/SearchAutocomplete.tsx
+++ b/packages/@react-spectrum/autocomplete/src/SearchAutocomplete.tsx
@@ -172,7 +172,7 @@ function _SearchAutocompleteBase<T extends object>(props: SpectrumSearchAutocomp
           {...listBoxProps}
           ref={listBoxRef}
           disallowEmptySelection
-          autoFocus={state.focusStrategy}
+          autoFocus={state.focusStrategy ?? undefined}
           shouldSelectOnPressUp
           focusOnPointerEnter
           layout={layout}
diff --git a/packages/@react-spectrum/tabs/src/Tabs.tsx b/packages/@react-spectrum/tabs/src/Tabs.tsx
index 99d93271320..0ebfd3a8c13 100644
--- a/packages/@react-spectrum/tabs/src/Tabs.tsx
+++ b/packages/@react-spectrum/tabs/src/Tabs.tsx
@@ -12,13 +12,14 @@
 
 import {AriaTabPanelProps, SpectrumTabListProps, SpectrumTabPanelsProps, SpectrumTabsProps} from '@react-types/tabs';
 import {classNames, SlotProvider, unwrapDOMRef, useDOMRef, useStyleProps} from '@react-spectrum/utils';
-import {DOMProps, DOMRef, Key, Node, Orientation, StyleProps} from '@react-types/shared';
+import {DOMProps, DOMRef, DOMRefValue, Key, Node, Orientation, RefObject, StyleProps} from '@react-types/shared';
 import {filterDOMProps, mergeProps, useId, useLayoutEffect, useResizeObserver} from '@react-aria/utils';
 import {FocusRing} from '@react-aria/focus';
 import {Item, Picker} from '@react-spectrum/picker';
 import {ListCollection} from '@react-stately/list';
 import React, {
-  MutableRefObject,
+  CSSProperties,
+  HTMLAttributes,
   ReactElement,
   ReactNode,
   useCallback,
@@ -40,22 +41,20 @@ import {useTab, useTabList, useTabPanel} from '@react-aria/tabs';
 interface TabsContext<T> {
   tabProps: SpectrumTabsProps<T>,
   tabState: {
-    tabListState: TabListState<T>,
+    tabListState: TabListState<T> | null,
     setTabListState: (state: TabListState<T>) => void,
-    selectedTab: HTMLElement,
+    selectedTab: HTMLElement | null,
     collapsed: boolean
   },
   refs: {
-    wrapperRef: MutableRefObject<HTMLDivElement>,
-    tablistRef: MutableRefObject<HTMLDivElement>
-  },
-  tabPanelProps: {
-    'aria-labelledby': string
+    wrapperRef: RefObject<HTMLDivElement | null>,
+    tablistRef: RefObject<HTMLDivElement | null>
   },
+  tabPanelProps: HTMLAttributes<HTMLElement>,
   tabLineState: Array<DOMRect>
 }
 
-const TabContext = React.createContext<TabsContext<any>>(null);
+const TabContext = React.createContext<TabsContext<any> | null>(null);
 
 function Tabs<T extends object>(props: SpectrumTabsProps<T>, ref: DOMRef<HTMLDivElement>) {
   props = useProviderProps(props);
@@ -67,20 +66,20 @@ function Tabs<T extends object>(props: SpectrumTabsProps<T>, ref: DOMRef<HTMLDiv
   } = props;
 
   let domRef = useDOMRef(ref);
-  let tablistRef = useRef<HTMLDivElement>(undefined);
-  let wrapperRef = useRef<HTMLDivElement>(undefined);
+  let tablistRef = useRef<HTMLDivElement>(null);
+  let wrapperRef = useRef<HTMLDivElement>(null);
 
   let {direction} = useLocale();
   let {styleProps} = useStyleProps(otherProps);
   let [collapsed, setCollapsed] = useState(false);
-  let [selectedTab, setSelectedTab] = useState<HTMLElement>();
-  const [tabListState, setTabListState] = useState<TabListState<T>>(null);
-  let [tabPositions, setTabPositions] = useState([]);
-  let prevTabPositions = useRef(tabPositions);
+  let [selectedTab, setSelectedTab] = useState<HTMLElement | null>(null);
+  const [tabListState, setTabListState] = useState<TabListState<T> | null>(null);
+  let [tabPositions, setTabPositions] = useState<DOMRect[]>([]);
+  let prevTabPositions = useRef<DOMRect[]>(tabPositions);
 
   useEffect(() => {
     if (tablistRef.current) {
-      let selectedTab: HTMLElement = tablistRef.current.querySelector(`[data-key="${CSS.escape(tabListState?.selectedKey?.toString())}"]`);
+      let selectedTab: HTMLElement | null = tablistRef.current.querySelector(`[data-key="${CSS.escape(tabListState?.selectedKey?.toString() ?? '')}"]`);
 
       if (selectedTab != null) {
         setSelectedTab(selectedTab);
@@ -92,15 +91,16 @@ function Tabs<T extends object>(props: SpectrumTabsProps<T>, ref: DOMRef<HTMLDiv
   let checkShouldCollapse = useCallback(() => {
     if (wrapperRef.current && orientation !== 'vertical') {
       let tabsComponent = wrapperRef.current;
-      let tabs = tablistRef.current.querySelectorAll('[role="tab"]');
-      let tabDimensions = [...tabs].map(tab => tab.getBoundingClientRect());
+      let tabs: NodeListOf<Element> = tablistRef.current?.querySelectorAll('[role="tab"]') ?? new NodeList() as NodeListOf<Element>;
+      let tabDimensions = [...tabs].map((tab: Element) => tab.getBoundingClientRect());
 
       let end = direction === 'rtl' ? 'left' : 'right';
       let farEdgeTabList = tabsComponent.getBoundingClientRect()[end];
       let farEdgeLastTab = tabDimensions[tabDimensions.length - 1][end];
       let shouldCollapse = direction === 'rtl' ? farEdgeLastTab < farEdgeTabList : farEdgeTabList < farEdgeLastTab;
       setCollapsed(shouldCollapse);
-      if (tabDimensions.length !== prevTabPositions.current.length || tabDimensions.some((box, index) => box?.left !== prevTabPositions.current[index]?.left || box?.right !== prevTabPositions.current[index]?.right)) {
+      if (tabDimensions.length !== prevTabPositions.current.length
+        || tabDimensions.some((box, index) => box?.left !== prevTabPositions.current[index]?.left || box?.right !== prevTabPositions.current[index]?.right)) {
         setTabPositions(tabDimensions);
         prevTabPositions.current = tabDimensions;
       }
@@ -113,7 +113,7 @@ function Tabs<T extends object>(props: SpectrumTabsProps<T>, ref: DOMRef<HTMLDiv
 
   useResizeObserver({ref: wrapperRef, onResize: checkShouldCollapse});
 
-  let tabPanelProps = {
+  let tabPanelProps: HTMLAttributes<HTMLElement> = {
     'aria-labelledby': undefined
   };
 
@@ -202,8 +202,8 @@ function Tab<T>(props: TabProps<T>) {
 
 interface TabLineProps {
   orientation?: Orientation,
-  selectedTab?: HTMLElement,
-  selectedKey?: Key
+  selectedTab?: HTMLElement | null,
+  selectedKey?: Key | null
 }
 
 // @private
@@ -218,18 +218,20 @@ function TabLine(props: TabLineProps) {
 
   let {direction} = useLocale();
   let {scale} = useProvider();
-  let {tabLineState} = useContext(TabContext);
+  let {tabLineState} = useContext(TabContext)!;
 
-  let [style, setStyle] = useState({
+  let [style, setStyle] = useState<CSSProperties>({
     width: undefined,
     height: undefined
   });
 
   let onResize = useCallback(() => {
     if (selectedTab) {
-      let styleObj = {transform: undefined, width: undefined, height: undefined};
+      let styleObj: CSSProperties = {transform: undefined, width: undefined, height: undefined};
       // In RTL, calculate the transform from the right edge of the tablist so that resizing the window doesn't break the Tabline position due to offsetLeft changes
-      let offset = direction === 'rtl' ? -1 * ((selectedTab.offsetParent as HTMLElement)?.offsetWidth - selectedTab.offsetWidth - selectedTab.offsetLeft) : selectedTab.offsetLeft;
+      let offset = direction === 'rtl' ?
+        -1 * ((selectedTab.offsetParent as HTMLElement)?.offsetWidth - selectedTab.offsetWidth - selectedTab.offsetLeft) :
+        selectedTab.offsetLeft;
       styleObj.transform = orientation === 'vertical'
         ? `translateY(${selectedTab.offsetTop}px)`
         : `translateX(${offset}px)`;
@@ -255,7 +257,7 @@ function TabLine(props: TabLineProps) {
  * The keys of the items within the <TabList> must match up with a corresponding item inside the <TabPanels>.
  */
 export function TabList<T>(props: SpectrumTabListProps<T>) {
-  const tabContext = useContext(TabContext);
+  const tabContext = useContext(TabContext)!;
   const {refs, tabState, tabProps, tabPanelProps} = tabContext;
   const {isQuiet, density, isEmphasized, orientation} = tabProps;
   const {selectedTab, collapsed, setTabListState} = tabState;
@@ -330,13 +332,13 @@ export function TabList<T>(props: SpectrumTabListProps<T>) {
  * TabPanels is used within Tabs as a container for the content of each tab.
  * The keys of the items within the <TabPanels> must match up with a corresponding item inside the <TabList>.
  */
-export function TabPanels<T>(props: SpectrumTabPanelsProps<T>) {
-  const {tabState, tabProps} = useContext(TabContext);
+export function TabPanels<T extends object>(props: SpectrumTabPanelsProps<T>) {
+  const {tabState, tabProps} = useContext(TabContext)!;
   const {tabListState} = tabState;
 
-  const factory = useCallback(nodes => new ListCollection(nodes), []);
+  const factory = useCallback((nodes: Iterable<Node<T>>) => new ListCollection(nodes), []);
   const collection = useCollection({items: tabProps.items, ...props}, factory, {suppressTextValueWarning: true});
-  const selectedItem = tabListState ? collection.getItem(tabListState.selectedKey) : null;
+  const selectedItem = tabListState && tabListState.selectedKey != null ? collection.getItem(tabListState.selectedKey) : null;
 
   return (
     <TabPanel {...props} key={tabListState?.selectedKey}>
@@ -351,9 +353,9 @@ interface TabPanelProps extends AriaTabPanelProps, StyleProps {
 
 // @private
 function TabPanel(props: TabPanelProps) {
-  const {tabState, tabPanelProps: ctxTabPanelProps} = useContext(TabContext);
+  const {tabState, tabPanelProps: ctxTabPanelProps} = useContext(TabContext)!;
   const {tabListState} = tabState;
-  let ref = useRef(undefined);
+  let ref = useRef<HTMLDivElement | null>(null);
   const {tabPanelProps} = useTabPanel(props, tabListState, ref);
   let {styleProps} = useStyleProps(props);
 
@@ -392,8 +394,8 @@ function TabPicker<T>(props: TabPickerProps<T>) {
     visible
   } = props;
 
-  let ref = useRef(undefined);
-  let [pickerNode, setPickerNode] = useState(null);
+  let ref = useRef<DOMRefValue<HTMLDivElement>>(null);
+  let [pickerNode, setPickerNode] = useState<HTMLElement | null>(null);
 
   useEffect(() => {
     let node = unwrapDOMRef(ref);
@@ -408,7 +410,6 @@ function TabPicker<T>(props: TabPickerProps<T>) {
 
   const style : React.CSSProperties = visible ? {} : {visibility: 'hidden', position: 'absolute'};
 
-  // TODO: Figure out if tabListProps should go onto the div here, v2 doesn't do it
   return (
     <div
       className={classNames(
diff --git a/packages/@react-stately/combobox/src/useComboBoxState.ts b/packages/@react-stately/combobox/src/useComboBoxState.ts
index 422b991707a..13f17f235da 100644
--- a/packages/@react-stately/combobox/src/useComboBoxState.ts
+++ b/packages/@react-stately/combobox/src/useComboBoxState.ts
@@ -28,7 +28,7 @@ export interface ComboBoxState<T> extends SelectState<T>, FormValidationState{
   /** Selects the currently focused item and updates the input value. */
   commit(): void,
   /** Controls which item will be auto focused when the menu opens. */
-  readonly focusStrategy: FocusStrategy,
+  readonly focusStrategy: FocusStrategy | null,
   /** Opens the menu. */
   open(focusStrategy?: FocusStrategy | null, trigger?: MenuTriggerAction): void,
   /** Toggles the menu. */
@@ -64,7 +64,7 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
 
   let [showAllItems, setShowAllItems] = useState(false);
   let [isFocused, setFocusedState] = useState(false);
-  let [focusStrategy, setFocusStrategy] = useState<FocusStrategy>(null);
+  let [focusStrategy, setFocusStrategy] = useState<FocusStrategy | null>(null);
 
   let onSelectionChange = (key) => {
     if (props.onSelectionChange) {
@@ -79,15 +79,29 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
     }
   };
 
-  let {collection, selectionManager, selectedKey, setSelectedKey, selectedItem, disabledKeys} = useSingleSelectListState({
+  let {collection,
+    selectionManager,
+    selectedKey,
+    setSelectedKey,
+    selectedItem,
+    disabledKeys
+  } = useSingleSelectListState({
     ...props,
     onSelectionChange,
     items: props.items ?? props.defaultItems
   });
+  let defaultInputValue: string | null | undefined = props.defaultInputValue;
+  if (defaultInputValue == null) {
+    if (selectedKey == null) {
+      defaultInputValue = '';
+    } else {
+      defaultInputValue = collection.getItem(selectedKey)?.textValue ?? '';
+    }
+  }
 
   let [inputValue, setInputValue] = useControlledState(
     props.inputValue,
-    props.defaultInputValue ?? collection.getItem(selectedKey)?.textValue ?? '',
+    defaultInputValue!,
     props.onInputChange
   );
 
@@ -102,7 +116,7 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
   let [lastCollection, setLastCollection] = useState(filteredCollection);
 
   // Track what action is attempting to open the menu
-  let menuOpenTrigger = useRef('focus' as MenuTriggerAction);
+  let menuOpenTrigger = useRef<MenuTriggerAction | undefined>('focus');
   let onOpenChange = (open: boolean) => {
     if (props.onOpenChange) {
       props.onOpenChange(open, open ? menuOpenTrigger.current : undefined);
@@ -115,7 +129,7 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
   };
 
   let triggerState = useOverlayTriggerState({...props, onOpenChange, isOpen: undefined, defaultOpen: undefined});
-  let open = (focusStrategy: FocusStrategy = null, trigger?: MenuTriggerAction) => {
+  let open = (focusStrategy: FocusStrategy | null = null, trigger?: MenuTriggerAction) => {
     let displayAllItems = (trigger === 'manual' || (trigger === 'focus' && menuTrigger === 'focus'));
     // Prevent open operations from triggering if there is nothing to display
     // Also prevent open operations from triggering if items are uncontrolled but defaultItems is empty, even if displayAllItems is true.
@@ -132,7 +146,7 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
     }
   };
 
-  let toggle = (focusStrategy: FocusStrategy = null, trigger?: MenuTriggerAction) => {
+  let toggle = (focusStrategy: FocusStrategy | null = null, trigger?: MenuTriggerAction) => {
     let displayAllItems = (trigger === 'manual' || (trigger === 'focus' && menuTrigger === 'focus'));
     // If the menu is closed and there is nothing to display, early return so toggle isn't called to prevent extraneous onOpenChange
     if (!(allowsEmptyCollection || filteredCollection.size > 0 || (displayAllItems && originalCollection.size > 0) || props.items) && !triggerState.isOpen) {
@@ -158,7 +172,7 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
 
   // If menu is going to close, save the current collection so we can freeze the displayed collection when the
   // user clicks outside the popover to close the menu. Prevents the menu contents from updating as the menu closes.
-  let toggleMenu = useCallback((focusStrategy: FocusStrategy = null) => {
+  let toggleMenu = useCallback((focusStrategy: FocusStrategy | null = null) => {
     if (triggerState.isOpen) {
       updateLastCollection();
     }
@@ -176,13 +190,15 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
 
   let [lastValue, setLastValue] = useState(inputValue);
   let resetInputValue = () => {
-    let itemText = collection.getItem(selectedKey)?.textValue ?? '';
+    let itemText = selectedKey != null ? collection.getItem(selectedKey)?.textValue ?? '' : '';
     setLastValue(itemText);
     setInputValue(itemText);
   };
 
   let lastSelectedKey = useRef(props.selectedKey ?? props.defaultSelectedKey ?? null);
-  let lastSelectedKeyText = useRef(collection.getItem(selectedKey)?.textValue ?? '');
+  let lastSelectedKeyText = useRef(
+    selectedKey != null ? collection.getItem(selectedKey)?.textValue ?? '' : ''
+  );
   // intentional omit dependency array, want this to happen on every render
   // eslint-disable-next-line react-hooks/exhaustive-deps
   useEffect(() => {
@@ -245,7 +261,7 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
     // This is to handle cases where a selectedKey is specified but the items aren't available (async loading) or the selected item's text value updates.
     // Only reset if the user isn't currently within the field so we don't erroneously modify user input.
     // If inputValue is controlled, it is the user's responsibility to update the inputValue when items change.
-    let selectedItemText = collection.getItem(selectedKey)?.textValue ?? '';
+    let selectedItemText = selectedKey != null ? collection.getItem(selectedKey)?.textValue ?? '' : '';
     if (!isFocused && selectedKey != null && props.inputValue === undefined && selectedKey === lastSelectedKey.current) {
       if (lastSelectedKeyText.current !== selectedItemText) {
         setLastValue(selectedItemText);
@@ -280,10 +296,10 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
   let commitSelection = () => {
     // If multiple things are controlled, call onSelectionChange
     if (props.selectedKey !== undefined && props.inputValue !== undefined) {
-      props.onSelectionChange(selectedKey);
+      props.onSelectionChange?.(selectedKey);
 
       // Stop menu from reopening from useEffect
-      let itemText = collection.getItem(selectedKey)?.textValue ?? '';
+      let itemText = selectedKey != null ? collection.getItem(selectedKey)?.textValue ?? '' : '';
       setLastValue(itemText);
       closeMenu();
     } else {
@@ -295,7 +311,7 @@ export function useComboBoxState<T extends object>(props: ComboBoxStateOptions<T
 
   const commitValue = () => {
     if (allowsCustomValue) {
-      const itemText = collection.getItem(selectedKey)?.textValue ?? '';
+      const itemText = selectedKey != null ? collection.getItem(selectedKey)?.textValue ?? '' : '';
       (inputValue === itemText) ? commitSelection() : commitCustomValue();
     } else {
       // Reset inputValue and close menu
@@ -376,7 +392,7 @@ function filterCollection<T extends object>(collection: Collection<Node<T>>, inp
 }
 
 function filterNodes<T>(collection: Collection<Node<T>>, nodes: Iterable<Node<T>>, inputValue: string, filter: FilterFn): Iterable<Node<T>> {
-  let filteredNode = [];
+  let filteredNode: Node<T>[] = [];
   for (let node of nodes) {
     if (node.type === 'section' && node.hasChildNodes) {
       let filtered = filterNodes(collection, getChildNodes(node, collection), inputValue, filter);
diff --git a/packages/@react-stately/list/src/ListCollection.ts b/packages/@react-stately/list/src/ListCollection.ts
index 63e477f182d..28c3d3f620b 100644
--- a/packages/@react-stately/list/src/ListCollection.ts
+++ b/packages/@react-stately/list/src/ListCollection.ts
@@ -15,8 +15,8 @@ import {Collection, Key, Node} from '@react-types/shared';
 export class ListCollection<T> implements Collection<Node<T>> {
   private keyMap: Map<Key, Node<T>> = new Map();
   private iterable: Iterable<Node<T>>;
-  private firstKey: Key;
-  private lastKey: Key;
+  private firstKey: Key | null = null;
+  private lastKey: Key | null = null;
 
   constructor(nodes: Iterable<Node<T>>) {
     this.iterable = nodes;
@@ -35,7 +35,7 @@ export class ListCollection<T> implements Collection<Node<T>> {
       visit(node);
     }
 
-    let last: Node<T>;
+    let last: Node<T> | null = null;
     let index = 0;
     for (let [key, node] of this.keyMap) {
       if (last) {
@@ -57,7 +57,7 @@ export class ListCollection<T> implements Collection<Node<T>> {
       last.nextKey = undefined;
     }
 
-    this.lastKey = last?.key;
+    this.lastKey = last?.key ?? null;
   }
 
   *[Symbol.iterator]() {
@@ -74,12 +74,12 @@ export class ListCollection<T> implements Collection<Node<T>> {
 
   getKeyBefore(key: Key) {
     let node = this.keyMap.get(key);
-    return node ? node.prevKey : null;
+    return node ? node.prevKey ?? null : null;
   }
 
   getKeyAfter(key: Key) {
     let node = this.keyMap.get(key);
-    return node ? node.nextKey : null;
+    return node ? node.nextKey ?? null : null;
   }
 
   getFirstKey() {
@@ -91,7 +91,7 @@ export class ListCollection<T> implements Collection<Node<T>> {
   }
 
   getItem(key: Key) {
-    return this.keyMap.get(key);
+    return this.keyMap.get(key) ?? null;
   }
 
   at(idx: number) {
diff --git a/packages/@react-stately/list/src/useListState.ts b/packages/@react-stately/list/src/useListState.ts
index 92e5f9c92fd..c6018bb0a45 100644
--- a/packages/@react-stately/list/src/useListState.ts
+++ b/packages/@react-stately/list/src/useListState.ts
@@ -57,31 +57,31 @@ export function useListState<T extends object>(props: ListProps<T>): ListState<T
   );
 
   // Reset focused key if that item is deleted from the collection.
-  const cachedCollection = useRef(null);
+  const cachedCollection = useRef<Collection<Node<T>> | null>(null);
   useEffect(() => {
-    if (selectionState.focusedKey != null && !collection.getItem(selectionState.focusedKey)) {
+    if (selectionState.focusedKey != null && !collection.getItem(selectionState.focusedKey) && cachedCollection.current) {
       const startItem = cachedCollection.current.getItem(selectionState.focusedKey);
       const cachedItemNodes = [...cachedCollection.current.getKeys()].map(
         key => {
-          const itemNode = cachedCollection.current.getItem(key);
-          return itemNode.type === 'item' ? itemNode : null;
+          const itemNode = cachedCollection.current!.getItem(key);
+          return itemNode?.type === 'item' ? itemNode : null;
         }
       ).filter(node => node !== null);
       const itemNodes = [...collection.getKeys()].map(
         key => {
           const itemNode = collection.getItem(key);
-          return itemNode.type === 'item' ? itemNode : null;
+          return itemNode?.type === 'item' ? itemNode : null;
         }
       ).filter(node => node !== null);
-      const diff = cachedItemNodes.length - itemNodes.length;
+      const diff: number = (cachedItemNodes?.length ?? 0) - (itemNodes?.length ?? 0);
       let index = Math.min(
         (
           diff > 1 ?
-          Math.max(startItem.index - diff + 1, 0) :
-          startItem.index
+          Math.max((startItem?.index ?? 0) - diff + 1, 0) :
+          startItem?.index ?? 0
         ),
-        itemNodes.length - 1);
-      let newNode:Node<T>;
+        (itemNodes?.length ?? 0) - 1);
+      let newNode: Node<T> | null = null;
       let isReverseSearching = false;
       while (index >= 0) {
         if (!selectionManager.isDisabled(itemNodes[index].key)) {
@@ -94,8 +94,8 @@ export function useListState<T extends object>(props: ListProps<T>): ListState<T
         // Otherwise, find previous, not disabled item.
         } else {
           isReverseSearching = true;
-          if (index > startItem.index) {
-            index = startItem.index;
+          if (index > (startItem?.index ?? 0)) {
+            index = (startItem?.index ?? 0);
           }
           index--;
         }
diff --git a/packages/@react-stately/list/src/useSingleSelectListState.ts b/packages/@react-stately/list/src/useSingleSelectListState.ts
index 1126aabdb43..b99a98af8ad 100644
--- a/packages/@react-stately/list/src/useSingleSelectListState.ts
+++ b/packages/@react-stately/list/src/useSingleSelectListState.ts
@@ -10,7 +10,7 @@
  * governing permissions and limitations under the License.
  */
 
-import {CollectionStateBase, Key, Node, SingleSelection} from '@react-types/shared';
+import {CollectionStateBase, Key, Node, Selection, SingleSelection} from '@react-types/shared';
 import {ListState, useListState} from './useListState';
 import {useControlledState} from '@react-stately/utils';
 import {useMemo} from 'react';
@@ -24,7 +24,7 @@ export interface SingleSelectListProps<T> extends CollectionStateBase<T>, Omit<S
 
 export interface SingleSelectListState<T> extends ListState<T> {
   /** The key for the currently selected item. */
-  readonly selectedKey: Key,
+  readonly selectedKey: Key | null,
 
   /** Sets the selected key. */
   setSelectedKey(key: Key | null): void,
@@ -46,7 +46,11 @@ export function useSingleSelectListState<T extends object>(props: SingleSelectLi
     disallowEmptySelection: true,
     allowDuplicateSelectionEvents: true,
     selectedKeys,
-    onSelectionChange: (keys: Set<Key>) => {
+    onSelectionChange: (keys: Selection) => {
+      // impossible, but TS doesn't know that
+      if (keys === 'all') {
+        return;
+      }
       let key = keys.values().next().value ?? null;
 
       // Always fire onSelectionChange, even if the key is the same
diff --git a/packages/@react-stately/select/src/useSelectState.ts b/packages/@react-stately/select/src/useSelectState.ts
index 0c19849b33b..f02cf7adb24 100644
--- a/packages/@react-stately/select/src/useSelectState.ts
+++ b/packages/@react-stately/select/src/useSelectState.ts
@@ -27,7 +27,7 @@ export interface SelectState<T> extends SingleSelectListState<T>, OverlayTrigger
   setFocused(isFocused: boolean): void,
 
   /** Controls which item will be auto focused when the menu opens. */
-  readonly focusStrategy: FocusStrategy,
+  readonly focusStrategy: FocusStrategy | null,
 
   /** Opens the menu. */
   open(focusStrategy?: FocusStrategy | null): void,
diff --git a/packages/@react-stately/selection/src/types.ts b/packages/@react-stately/selection/src/types.ts
index c116cb07384..fcc2b1c346f 100644
--- a/packages/@react-stately/selection/src/types.ts
+++ b/packages/@react-stately/selection/src/types.ts
@@ -23,7 +23,7 @@ export interface FocusState {
   /** Whether the first or last child of the focused key should receive focus. */
   readonly childFocusStrategy: FocusStrategy,
   /** Sets the focused key, and optionally, whether the first or last child of that key should receive focus. */
-  setFocusedKey(key: Key, child?: FocusStrategy): void
+  setFocusedKey(key: Key | null, child?: FocusStrategy): void
 }
 
 export interface SingleSelectionState extends FocusState {
diff --git a/packages/@react-stately/steplist/src/useStepListState.ts b/packages/@react-stately/steplist/src/useStepListState.ts
index e63d8316794..7dddc99999a 100644
--- a/packages/@react-stately/steplist/src/useStepListState.ts
+++ b/packages/@react-stately/steplist/src/useStepListState.ts
@@ -41,7 +41,7 @@ export function useStepListState<T extends object>(props: StepListProps<T>): Ste
   let [lastCompletedStep, setLastCompletedStep] = useControlledState<Key | null>(props.lastCompletedStep, props.defaultLastCompletedStep ?? null, props.onLastCompletedStepChange);
   const {setSelectedKey: realSetSelectedKey, selectedKey, collection} = state;
   const {indexMap, keysLinkedList} = useMemo(() => buildKeysMaps(collection), [collection]);
-  const selectedIdx = indexMap.get(selectedKey);
+  const selectedIdx = selectedKey != null ? indexMap.get(selectedKey) : 0;
 
   const isCompleted = useCallback((step: Key | null | undefined) => {
     if (step === undefined) {
@@ -71,7 +71,7 @@ export function useStepListState<T extends object>(props: StepListProps<T>): Ste
   useEffect(() => {
     // Ensure a step is always selected (in case no selected key was specified or if selected item was deleted from collection)
     let selectedKey: Key | null = state.selectedKey;
-    if (state.selectionManager.isEmpty || !state.collection.getItem(selectedKey)) {
+    if (state.selectionManager.isEmpty || selectedKey == null || !state.collection.getItem(selectedKey)) {
       selectedKey = findDefaultSelectedKey(state.collection, state.disabledKeys);
       if (selectedKey !== null) {
         state.selectionManager.replaceSelection(selectedKey);
diff --git a/packages/@react-types/combobox/src/index.d.ts b/packages/@react-types/combobox/src/index.d.ts
index 750b552a050..5b96371b82e 100644
--- a/packages/@react-types/combobox/src/index.d.ts
+++ b/packages/@react-types/combobox/src/index.d.ts
@@ -36,7 +36,7 @@ export type MenuTriggerAction = 'focus' | 'input' | 'manual';
 
 export interface ComboBoxValidationValue {
   /** The selected key in the ComboBox. */
-  selectedKey: Key,
+  selectedKey: Key | null,
   /** The value of the ComboBox input. */
   inputValue: string
 }
diff --git a/scripts/compareAPIs.js b/scripts/compareAPIs.js
index 8a8f1925236..784f5cd3111 100644
--- a/scripts/compareAPIs.js
+++ b/scripts/compareAPIs.js
@@ -122,7 +122,18 @@ async function compare() {
         changes.push(`
 #### ${simplifiedName}
 ${changedByDeps.length > 0 ? `changed by:
- - ${changedByDeps.join('\n - ')}\n\n` : ''}${diff.split('\n').filter(line => line !== ' ').join('\n')}${affected.length > 0 ? `
+ - ${changedByDeps.join('\n - ')}\n\n` : ''}${diff.split('\n').filter(line => line !== ' ').join('\n')}${
+// eslint-disable-next-line no-nested-ternary
+affected.length > 0 ?
+argv.isCI ? `
+<details>
+  <summary>it changed</summary>
+   <ul>
+     <li>${affected.join('</li>\n<li>')}</li>
+   </ul>
+</details>
+`
+  : `
 it changed:
  - ${affected.join('\n - ')}
 ` : ''}
diff --git a/tsconfig.json b/tsconfig.json
index 61df7feffbf..bc6ffbb927c 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -102,6 +102,7 @@
           "./packages/@react-spectrum/steplist",
           "./packages/@react-spectrum/story-utils",
           "./packages/@react-spectrum/switch",
+          "./packages/@react-spectrum/tabs",
           "./packages/@react-spectrum/tag",
           "./packages/@react-spectrum/text",
           "./packages/@react-spectrum/textfield",
@@ -114,12 +115,14 @@
           "./packages/@react-stately/calendar",
           "./packages/@react-stately/checkbox",
           "./packages/@react-stately/color",
+          "./packages/@react-stately/combobox",
+          "./packages/@react-stately/list",
           "./packages/@react-stately/numberfield",
           "./packages/@react-stately/overlays",
           "./packages/@react-stately/pagination",
+          "./packages/@react-stately/radio",
           "./packages/@react-stately/searchfield",
           "./packages/@react-stately/steplist",
-          "./packages/@react-stately/radio",
           "./packages/@react-stately/toggle",
           "./packages/@react-stately/utils",
           "./packages/@react-types/a",