fix(runtime-core): Avoid mutating original options object in createApp (#4840)

fix #4398

packages/runtime-core/__tests__/helpers/resolveAssets.spec.ts

@@ -91,9 +91,9 @@ describe('resolveAssets', () => {
     const root = nodeOps.createElement('div')
     app.mount(root)
 
-    expect(component1!).toBe(Root) // explicit self name reference
+    expect(component1!).toMatchObject(Root) // explicit self name reference
     expect(component2!).toBe(Foo) // successful resolve take higher priority
-    expect(component3!).toBe(Root) // fallback when resolve fails
+    expect(component3!).toMatchObject(Root) // fallback when resolve fails
   })
 
   describe('warning', () => {

packages/runtime-core/src/apiCreateApp.ts

@@ -179,6 +179,11 @@ export function createAppAPI<HostElement>(
   hydrate?: RootHydrateFunction
 ): CreateAppFunction<HostElement> {
   return function createApp(rootComponent, rootProps = null) {
+
+    if (!isFunction(rootComponent)) {
+      rootComponent = { ...rootComponent }
+    }
+
     if (rootProps != null && !isObject(rootProps)) {
       __DEV__ && warn(`root props passed to app.mount() must be an object.`)
       rootProps = null