Questions
Q:

FirebaseOptions cannot be null when creating the default app

I got this FirebaseOptions cannot be null error in when i run flutter application,

Error: Assertion failed: file:///C:/Users/Matt/AppData/Local/Pub/Cache/hosted/pub.dartlang.org/firebase_core_web-1.5.4/lib/src/firebase_core_web.dart:273:11
options != null
"FirebaseOptions cannot be null when creating the default app."
    at Object.throw_ [as throw] (http://localhost:57554/dart_sdk.js:5386:11)
    at Object.assertFailed (http://localhost:57554/dart_sdk.js:5308:15)
    at firebase_core_web.FirebaseCoreWeb.new.initializeApp (http://localhost:57554/packages/firebase_core_web/firebase_core_web.dart.lib.js:265:42)
    at initializeApp.next ()
    at http://localhost:57554/dart_sdk.js:42610:33
    at _RootZone.runUnary (http://localhost:57554/dart_sdk.js:42466:58)
    at _FutureListener.thenAwait.handleValue (http://localhost:57554/dart_sdk.js:37033:29)
    at handleValueCallback (http://localhost:57554/dart_sdk.js:37636:49)
    at Function._propagateToListeners (http://localhost:57554/dart_sdk.js:37674:17)
    at _Future.new.[_completeWithValue] (http://localhost:57554/dart_sdk.js:37516:23)
    at async._AsyncCallbackEntry.new.callback (http://localhost:57554/dart_sdk.js:37539:35)
    at Object._microtaskLoop (http://localhost:57554/dart_sdk.js:42771:13)
    at _startMicrotaskLoop (http://localhost:57554/dart_sdk.js:42777:13)
    at http://localhost:57554/dart_sdk.js:37905:9