diff --git a/src/pages/MarkerClusterSpiderfy/MarkerClusterSpiderfy.tsx b/src/pages/MarkerClusterSpiderfy/MarkerClusterSpiderfy.tsx
index c12ae58..f9993de 100644
--- a/src/pages/MarkerClusterSpiderfy/MarkerClusterSpiderfy.tsx
+++ b/src/pages/MarkerClusterSpiderfy/MarkerClusterSpiderfy.tsx
@@ -7,8 +7,9 @@ import createClusterIcon from './utils/createClusterIcon';
 import getMapData from './getMapData';
 import processFeatures from './processFeatures';
 import { CLUSTER_OPTIONS, CLUSTER_STYLES, lineStyles } from './mapStyles';
-import type { ClusterOptions, MapSuperClusterFeature } from './types';
-import { GeoJsonObject } from 'geojson';
+import type { ClusterOptions, DataRecord } from './types';
+import type { GeoJsonObject } from 'geojson';
+import rawData from './data.json';
 
 interface MarkerClusterSpiderProps {
   clusterOptions?: ClusterOptions;
@@ -125,7 +126,7 @@ const MarkerClusterSpider: FunctionComponent<MarkerClusterSpiderProps> = ({
 
     return processFeatures(
       mapInstance,
-      getMapData(mapInstance) as MapSuperClusterFeature[],
+      getMapData(mapInstance, rawData as DataRecord[]),
       clusterOptions
     );
   }, [mapInstance, zoom, center]);
diff --git a/src/pages/MarkerClusterSpiderfy/getMapData.test.ts b/src/pages/MarkerClusterSpiderfy/getMapData.test.ts
index d4c8627..84a6f93 100644
--- a/src/pages/MarkerClusterSpiderfy/getMapData.test.ts
+++ b/src/pages/MarkerClusterSpiderfy/getMapData.test.ts
@@ -1,9 +1,11 @@
 import { describe, expect, it } from 'vitest';
 import getMapData, {
   filterPointFeaturesWithinBoundingBox,
-  isCoordWithingBoundingBox,
+  isCoordWithinBoundingBox,
 } from './getMapData';
 import L from 'leaflet';
+import rawData from './data.json';
+import { DataRecord } from './types';
 
 const fakeClusterData = [
   {
@@ -128,14 +130,15 @@ describe('getMapData', () => {
       new L.Map(document.createElement('div'), {
         center: [52.370216, 4.895168],
         zoom: 7,
-      })
+      }),
+      rawData as DataRecord[]
     );
     expect(mapData).toEqual(fakeClusterData);
   });
 
-  it('isCoordWithingBoundingBox checks coordinates truly inside bounding box', () => {
-    expect(isCoordWithingBoundingBox([10, 10, 20, 20], [15, 15])).toBe(true);
-    expect(isCoordWithingBoundingBox([10, 10, 20, 20], [5, 33])).toBe(false);
+  it('isCoordWithinBoundingBox checks coordinates truly inside bounding box', () => {
+    expect(isCoordWithinBoundingBox([10, 10, 20, 20], [15, 15])).toBe(true);
+    expect(isCoordWithinBoundingBox([10, 10, 20, 20], [5, 33])).toBe(false);
   });
 
   it('filterPointFeaturesWithinBoundingBox checks features are truly inside bounding box', () => {
diff --git a/src/pages/MarkerClusterSpiderfy/getMapData.ts b/src/pages/MarkerClusterSpiderfy/getMapData.ts
index 92aaaef..eb88156 100644
--- a/src/pages/MarkerClusterSpiderfy/getMapData.ts
+++ b/src/pages/MarkerClusterSpiderfy/getMapData.ts
@@ -1,14 +1,11 @@
 import type { LatLngTuple } from 'leaflet';
-import Supercluster, { AnyProps, PointFeature } from 'supercluster';
-import { Feature, Geometry } from 'geojson';
+import Supercluster, { PointFeature } from 'supercluster';
+import { BBox, Feature, GeoJsonProperties, Geometry, Point } from 'geojson';
 import { toGeoJSON } from '@/utils/toGeoJSON';
-import toBoundsLiteral from '@/utils/toBoundsLiteral';
-import { DataRecord } from './types';
-import rawData from './data.json';
 
 // Simple util to check coords within a bounding box
-export const isCoordWithingBoundingBox = (
-  bbox: [number, number, number, number],
+export const isCoordWithinBoundingBox = (
+  bbox: BBox,
   coord: LatLngTuple,
   xIndex = 1,
   yIndex = 0
@@ -25,19 +22,17 @@ export const isCoordWithingBoundingBox = (
 };
 
 // Restrict data to that within specified bounding box
-export const filterPointFeaturesWithinBoundingBox = (
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  features: PointFeature<any>[],
-  bbox: [number, number, number, number]
+export const filterPointFeaturesWithinBoundingBox = <P>(
+  features: PointFeature<P>[],
+  bbox: BBox
 ) => {
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  const featuresFiltered: PointFeature<any>[] = [];
+  const featuresFiltered: PointFeature<P>[] = [];
 
   features.forEach(feature => {
     if (
-      isCoordWithingBoundingBox(
+      isCoordWithinBoundingBox(
         bbox,
-        feature.geometry.coordinates as LatLngTuple,
+        feature.geometry.coordinates as [number, number],
         0,
         1
       )
@@ -50,14 +45,17 @@ export const filterPointFeaturesWithinBoundingBox = (
 };
 
 // Helpful for cluster events to detect which cluster to follow
-const addExpansionZoom = (
+const addExpansionZoom = <D extends Supercluster.ClusterProperties>(
   superClusterIndex: Supercluster,
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  feature: Feature<Geometry, any>
+  feature: Feature<Geometry, D>
 ) => {
   try {
-    feature.properties.expansion_zoom =
-      superClusterIndex.getClusterExpansionZoom(feature.properties.cluster_id);
+    feature.properties = {
+      ...feature.properties,
+      expansion_zoom: superClusterIndex.getClusterExpansionZoom(
+        feature.properties.cluster_id
+      ),
+    };
   } catch (error) {
     console.error(
       "Can't add expansion zoom to cluster",
@@ -67,23 +65,30 @@ const addExpansionZoom = (
   }
 };
 
-const getMapData = (map: L.Map): PointFeature<AnyProps>[] => {
-  const bounds = toBoundsLiteral(map.getBounds()).flat() as [
-    number,
-    number,
-    number,
-    number,
+const getMapData = <D extends { geometry: Point }>(
+  map: L.Map,
+  rawData: D[]
+) => {
+  const bounds = map.getBounds();
+  const bbox: BBox = [
+    bounds.getWest(),
+    bounds.getSouth(),
+    bounds.getEast(),
+    bounds.getNorth(),
   ];
 
   // Save some resources by handling only data present in the current map view
   const featuresWithinBbox = filterPointFeaturesWithinBoundingBox(
-    toGeoJSON(rawData as DataRecord[]).features,
-    bounds
+    toGeoJSON(rawData).features,
+    bbox
   );
 
-  let clusters: PointFeature<AnyProps>[] = [];
+  type Dprops = (typeof featuresWithinBbox)[0];
 
-  const superClusterIndex = new Supercluster({
+  const superClusterIndex = new Supercluster<
+    Dprops['properties'],
+    Dprops['properties']
+  >({
     // Enable this for console.logs with the timing to build each cluster
     log: false,
     radius: 40,
@@ -93,15 +98,24 @@ const getMapData = (map: L.Map): PointFeature<AnyProps>[] => {
   }).load(featuresWithinBbox);
 
   if (superClusterIndex) {
-    clusters = superClusterIndex.getClusters(bounds, map.getZoom());
+    const clusters = superClusterIndex.getClusters(bbox, map.getZoom());
 
     for (const feature of clusters) {
-      // Used on cluster events to detect which cluster to zoom into
-      addExpansionZoom(superClusterIndex, feature);
+      if (isCluster(feature)) {
+        // Used on cluster events to detect which cluster to zoom into
+        addExpansionZoom(superClusterIndex, feature);
+      }
     }
+    return clusters;
   }
 
-  return clusters;
+  return [];
 };
 
+function isCluster<P extends GeoJsonProperties>(
+  feature: Supercluster.ClusterFeature<P> | PointFeature<P>
+): feature is Supercluster.ClusterFeature<P> {
+  return feature.properties?.cluster !== undefined;
+}
+
 export default getMapData;
diff --git a/src/pages/MarkerClusterSpiderfy/processFeatures.ts b/src/pages/MarkerClusterSpiderfy/processFeatures.ts
index 6e15220..69b6c78 100644
--- a/src/pages/MarkerClusterSpiderfy/processFeatures.ts
+++ b/src/pages/MarkerClusterSpiderfy/processFeatures.ts
@@ -81,7 +81,6 @@ const processFeatures = (
   for (const [, features] of Object.entries(markerItems)) {
     if (features.length === 1) {
       // Only one marker exists at this location so no modifications necessary
-      // markersFinal.push(features[0]);
       clusterItems.push(features[0]);
     } else {
       // Multiple markers exist at this location, therefore, prepare the zoomed in cluster markers
diff --git a/src/utils/toBoundsLiteral.ts b/src/utils/toBoundsLiteral.ts
index 081bfc9..6dbdbe5 100644
--- a/src/utils/toBoundsLiteral.ts
+++ b/src/utils/toBoundsLiteral.ts
@@ -1,14 +1,12 @@
-import { LatLngBounds } from 'leaflet';
+import type { LatLngBounds, LatLngBoundsLiteral } from 'leaflet';
 
-const toBoundsLiteral = (
-  bounds: LatLngBounds
-): [[number, number], [number, number]] => {
+const toBoundsLiteral = (bounds: LatLngBounds): LatLngBoundsLiteral => {
   const southWest = bounds.getSouthWest();
   const northEast = bounds.getNorthEast();
 
   return [
-    [southWest.lng as number, southWest.lat as number],
-    [northEast.lng as number, northEast.lat as number],
+    [southWest.lng, southWest.lat],
+    [northEast.lng, northEast.lat],
   ];
 };
 
diff --git a/src/utils/toGeoJSON.ts b/src/utils/toGeoJSON.ts
index 6ae0c95..62cf926 100644
--- a/src/utils/toGeoJSON.ts
+++ b/src/utils/toGeoJSON.ts
@@ -6,6 +6,10 @@ export function toGeoJSON<DataType extends { geometry: Geometry }>(
   type DataGeometry = DataType['geometry'];
   type DataProperties = Omit<DataType, 'geometry'>;
 
+  if (!data.length) {
+    throw new Error('Data was empty');
+  }
+
   const features = data.map(data => {
     const { geometry, ...other } = data;