title: Flutter: [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: PlatformException
body: <p>I am new in Flutter. I face a problem about <code>[ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: PlatformException</code>.</p>
  <p>Here is my Debug Console:</p>
  <pre><code>Launching lib\main.dart on sdk gphone x86 in debug mode...
  lib\main.dart:1
  √  Built build\app\outputs\flutter-apk\app-debug.apk.
  W/FlutterActivityAndFragmentDelegate(10702): A splash screen was provided to Flutter, but this is deprecated. See flutter.dev/go/android-splash-migration for migration steps.
  Connecting to VM Service at ws://127.0.0.1:59535/02E90npmd4s=/ws
  E/flutter (10702): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: PlatformException(network_error, com.google.android.gms.common.api.ApiException: 7: , null, null)
  E/flutter (10702): #0      StandardMethodCodec.decodeEnvelope
  package:flutter/…/services/message_codecs.dart:607
  E/flutter (10702): #1      MethodChannel._invokeMethod
  package:flutter/…/services/platform_channel.dart:156
  E/flutter (10702): &lt;asynchronous suspension&gt;
  E/flutter (10702): #2      MethodChannel.invokeMapMethod
  package:flutter/…/services/platform_channel.dart:356
  E/flutter (10702): &lt;asynchronous suspension&gt;
  E/flutter (10702): #3      GoogleSignIn._callMethod
  package:google_sign_in/google_sign_in.dart:244
  E/flutter (10702): &lt;asynchronous suspension&gt;
  E/flutter (10702): #4      GoogleSignIn.signIn.isCanceled (package:google_sign_in/google_sign_in.dart)
  E/flutter (10702): &lt;asynchronous suspension&gt;
  E/flutter (10702):
  </code></pre>
  <p>How do I fix it?</p>