fix: sign in toast issue (#4895)

frontend/appflowy_flutter/lib/core/helpers/url_launcher.dart

@@ -27,8 +27,7 @@ Future<bool> afLaunchUrl(
     );
   } on PlatformException catch (e) {
     Log.error('Failed to open uri: $e');
-  } finally {
-    result = false;
+    return false;
   }
 
   // if the uri is not a valid url, try to launch it with http scheme

frontend/appflowy_flutter/lib/startup/tasks/appflowy_cloud_task.dart

@@ -89,8 +89,10 @@ class AppFlowyCloudDeepLink {
       Log.error('onDeepLinkError: Unexpected empty deep link callback');
       _completer?.complete(FlowyResult.failure(AuthError.emptyDeepLink));
       _completer = null;
+      return;
     }
-    return _isAuthCallbackDeepLink(uri!).fold(
+
+    return _isAuthCallbackDeepLink(uri).fold(
       (_) async {
         final deviceId = await getDeviceId();
         final payload = OauthSignInPB(
@@ -101,8 +103,7 @@ class AppFlowyCloudDeepLink {
           },
         );
         _stateNotifier?.value = DeepLinkResult(state: DeepLinkState.loading);
-        final result =
-            await UserEventOauthSignIn(payload).send().then((value) => value);
+        final result = await UserEventOauthSignIn(payload).send();
 
         _stateNotifier?.value = DeepLinkResult(
           state: DeepLinkState.finish,

frontend/appflowy_flutter/lib/user/application/auth/af_cloud_auth_service.dart

@@ -72,8 +72,9 @@ class AppFlowyCloudAuthService implements AuthService {
             throw Exception('AppFlowyCloudDeepLink is not registered');
           }
         } else {
-          completer
-              .complete(FlowyResult.failure(AuthError.signInWithOauthError));
+          completer.complete(
+            FlowyResult.failure(AuthError.unableToGetDeepLink),
+          );
         }
 
         return completer.future;

frontend/appflowy_flutter/lib/user/application/auth/auth_error.dart

@@ -29,4 +29,8 @@ class AuthError {
   static final deepLinkError = FlowyError()
     ..msg = 'DeepLink error'
     ..code = ErrorCode.Internal;
+
+  static final unableToGetDeepLink = FlowyError()
+    ..msg = 'Unable to get the deep link'
+    ..code = ErrorCode.Internal;
 }