Resolve "Implement basic functionality"

Closes #1 (closed) Closes #2 (closed) Closes #3 (closed) Closes #4 (closed) Closes #5 (closed) Closes #6 (closed)

example/src/components/NumberCounter.vue

@@ -20,7 +20,10 @@
 export default {
   name: "NumberCounter",
   props: {
-    value: Number,
+    value: {
+      type: Number,
+      required: true,
+    },
   },
   emits: ["input"],
   data() {