chore: rm unneeded check from response

Author: russellwheatley

packages/firebase_core/firebase_core_platform_interface/lib/src/method_channel/method_channel_firebase.dart

@@ -28,10 +28,7 @@ class MethodChannelFirebase extends FirebasePlatform {
   Future<void> _initializeCore() async {
     List<CoreInitializeResponse> apps = await api.initializeCore();
 
-    apps
-        .where((element) => element != null)
-        .cast<CoreInitializeResponse>()
-        .forEach(_initializeFirebaseAppFromMap);
+    apps.cast<CoreInitializeResponse>().forEach(_initializeFirebaseAppFromMap);
     isCoreInitialized = true;
   }