title: TypeError: Cannot read property 'app' of undefined Error - Flutter using firebase Auth and Firestore in flutter web app
body: <pre><code> Running with sound null safety 
  TypeError: Cannot read property 'app' of undefined
      at Object.app$ [as app] (http://localhost:49841/packages/firebase_core_web/src/interop/core.dart.lib.js:42:101)
      at new cloud_firestore_web.FirebaseFirestoreWeb.new (http://localhost:49841/packages/cloud_firestore_web/src/write_batch_web.dart.lib.js:988:64)
      at Function.registerWith (http://localhost:49841/packages/cloud_firestore_web/src/write_batch_web.dart.lib.js:842:73)
      at Object.registerPlugins (http://localhost:49841/packages/nse7a/generated_plugin_registrant.dart.lib.js:33:46)
      at main (http://localhost:49841/web_entrypoint.dart.lib.js:41:35)
      at main.next (&lt;anonymous&gt;)
      at runBody (http://localhost:49841/dart_sdk.js:37229:34)
      at Object._async [as async] (http://localhost:49841/dart_sdk.js:37260:7)
      at main$ (http://localhost:49841/web_entrypoint.dart.lib.js:40:18)
      at http://localhost:49841/main_module.bootstrap.js:19:10
      at Array.forEach (&lt;anonymous&gt;)
      at window.$dartRunMain (http://localhost:49841/main_module.bootstrap.js:18:32)
      at &lt;anonymous&gt;:1:8
      at Object.runMain (http://localhost:49841/dwds/src/injected/client.js:8656:21)
      at http://localhost:49841/dwds/src/injected/client.js:22068:19
      at _wrapJsFunctionForAsync_closure.$protected (http://localhost:49841/dwds/src/injected/client.js:3830:15)
      at _wrapJsFunctionForAsync_closure.call$2 (http://localhost:49841/dwds/src/injected/client.js:10905:12)
      at Object._asyncStartSync (http://localhost:49841/dwds/src/injected/client.js:3794:20)
      at main__closure1.$call$body$main__closure (http://localhost:49841/dwds/src/injected/client.js:22080:16)
      at main__closure1.call$1 (http://localhost:49841/dwds/src/injected/client.js:22007:19)
      at StaticClosure._rootRunUnary [as call$2$5] (http://localhost:49841/dwds/src/injected/client.js:4153:16)
      at _CustomZone.runUnary$2$2 (http://localhost:49841/dwds/src/injected/client.js:12136:39)
      at _CustomZone.runUnaryGuarded$1$2 (http://localhost:49841/dwds/src/injected/client.js:12068:14)
      at _ControllerSubscription._sendData$1 (http://localhost:49841/dwds/src/injected/client.js:11697:19)
      at _DelayedData.perform$1 (http://localhost:49841/dwds/src/injected/client.js:11849:59)
      at _PendingEvents_schedule_closure.call$0 (http://localhost:49841/dwds/src/injected/client.js:11898:14)
      at Object._microtaskLoop (http://localhost:49841/dwds/src/injected/client.js:3990:24)
      at StaticClosure._startMicrotaskLoop (http://localhost:49841/dwds/src/injected/client.js:3996:11)
      at _AsyncRun__initializeScheduleImmediate_internalCallback.call$1 (http://localhost:49841/dwds/src/injected/client.js:10774:9)
      at invokeClosure (http://localhost:49841/dwds/src/injected/client.js:1250:26)
      at MutationObserver.&lt;anonymous&gt; (http://localhost:49841/dwds/src/injected/client.js:1269:18)
  ERROR - 2021-03-28 17:45:59.793377
  GET /web_entrypoint.dart.lib.js:40:18
  Error thrown by handler.
  FormatException: Illegal scheme character (at character 4)
  web_entrypoint.dart.lib.js:40:18
     ^
  
  dart:core                                                 _Uri.resolve
  package:flutter_tools/src/isolated/devfs_web.dart 503:57  WebAssetServer._resolveDartFile
  package:flutter_tools/src/isolated/devfs_web.dart 395:17  WebAssetServer.handleRequest
  package:dwds/src/handlers/injector.dart 110:32            DwdsInjector.middleware.&lt;fn&gt;.&lt;fn&gt;
  
  </code></pre>
  <pre><code>dependencies
  
     
  dependencies:
    flutter:
      SDK: flutter
  
    firebase_auth_web:
  
    # The following adds the Cupertino Icons font to your application.
    # Use the CupertinoIcons class for iOS style icons.
  
    cupertino_icons:
    firebase_auth:
    animated_splash_screen:
    provider:
    firebase_storage:
    cloud_firestore:
    firebase_core:
    json_annotation:
    curved_navigation_bar:
    shared_preferences:
  #  device_preview: ^0.5.5
    flutter_screenutil:
    url_launcher:
    flushbar:
    flutter_launcher_icons:
    image_picker:
  
  </code></pre>
  <p>index.html</p>
  <pre><code>`&lt;body&gt;
    &lt;!-- This script installs service_worker.js to provide PWA functionality to
         application. For more information, see:
         https://developers.google.com/web/fundamentals/primers/service-workers --&gt;
    &lt;script&gt;
      if ('serviceWorker' in navigator) {
        window.addEventListener('flutter-first-frame', function () {
          navigator.serviceWorker.register('flutter_service_worker.js');
        });
      }
    &lt;/script&gt;
    &lt;script&gt;
    // Your web app's Firebase configuration
    // For Firebase JS SDK v7.20.0 and later, measurementId is optional
    var firebaseConfig = {
      apiKey: &quot;********&quot;,
      authDomain: &quot;*******&quot;,
      databaseURL: &quot;https*******.com&quot;,
      projectId: &quot;******&quot;,
      storageBucket: &quot;nse7a-68809.appspot.com&quot;,
      messagingSenderId: &quot;******&quot;,
      appId: &quot;1:******&quot;,
      measurementId: &quot;G-F5XJN2HE8D&quot;
    };
    // Initialize Firebase
    firebase.initializeApp(firebaseConfig);
    firebase.analytics();
  &lt;/script&gt;
    &lt;script src=&quot;main.dart.js&quot; type=&quot;application/javascript&quot;&gt;&lt;/script&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  `
  </code></pre>