docs(VFab): usage example color issue

Author: johnleider

packages/docs/src/examples/v-fab/usage.vue

@@ -32,7 +32,7 @@
 
   const props = computed(() => {
     return {
-      color: color.value,
+      color: color.value || undefined,
       extended: extended.value || undefined,
       icon: !extended.value ? '$vuetify' : undefined,
       'prepend-icon': extended.value ? '$vuetify' : undefined,