MissingPluginException(No implementation found for method Firebase#initializeCore on channel plugins.flutter.io/firebase_core) code example

Example 1: MissingPluginException(No implementation found for method DocumentReference#setData on channel plugins.flutter.io/cloud_firestore

flutter clean
flutter packages get

Example 2: unhandled Exception: MissingPluginException(No implementation found for method Firebase#initializeCore on channel plugins.flutter.io/firebase_core)

Make sure your google-services.json file is copied into the correct folder