fix modelValue null handling

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@gwservices/fp-money",
-  "version": "2.0.2",
+  "version": "2.0.3-next.5",
   "private": false,
   "description": "Input formatter and currency selector",
   "repository": {
@@ -41,7 +41,8 @@
     "test": "vitest run",
     "testui": "vitest --ui",
     "coverage": "vitest run --coverage",
-    "vitestwatch": "vitest watch"
+    "vitestwatch": "vitest watch",
+    "deploy:next": "npm run build && npm version prerelease --no-git-tag-version --preid=next && npm publish"
   },
   "devDependencies": {
     "@rollup/plugin-typescript": "^11.1.6",

src/fp-money/component.vue

@@ -1,14 +1,16 @@
 <script lang="ts">
-import { defineComponent } from 'vue'
+import {defineComponent, PropType} from 'vue'
 import FPMoney, { Constructor, currencies, Values } from './fp-money'
 
 export default defineComponent({
   name: 'Fpmoney',
   emits: ['update:modelValue', 'update:currency', 'update:locale', 'update:format', 'update:display'],
   props: {
     modelValue: {
-      type: [String, Number],
-      required: true
+      type: [String, Number] as PropType<string | number | null>,
+      validator: (v): boolean => {
+        return ['string', 'number'].includes(typeof v) || v === null
+      }
     },
     currency: {
       type: String,