运行
flutter build appbundle时，出现以下错误：Gradle构建无法生成Android捆绑包。
在详细模式下运行时，这是我另外得到的：
#0 throwToolExit (package:flutter_tools/src/base/common.dart:24:3)
#1 _buildGradleProjectV2 (package:flutter_tools/src/android/gradle.dart:585:7)
<asynchronous suspension>
#2 buildGradleProject (package:flutter_tools/src/android/gradle.dart:331:14)
<asynchronous suspension>
#3 buildAppBundle (package:flutter_tools/src/android/app_bundle.dart:43:10)
<asynchronous suspension>
#4 BuildAppBundleCommand.runCommand (package:flutter_tools/src/commands/build_appbundle.dart:43:11)
<asynchronous suspension>
#5 FlutterCommand.verifyThenRunCommand (package:flutter_tools/src/runner/flutter_command.dart:545:18)
#6 _asyncThenWrapperHelper.<anonymous closure> (dart:async/runtime/libasync_patch.dart:77:64)
#7 _rootRunUnary (dart:async/zone.dart:1132:38)
#8 _CustomZone.runUnary (dart:async/zone.dart:1029:19)
#9 _FutureListener.handleValue (dart:async/future_impl.dart:126:18)
#10 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:639:45)
#11 Future._propagateToListeners (dart:async/future_impl.dart:668:32)
#12 Future._complete (dart:async/future_impl.dart:473:7)
#13 _SyncCompleter.complete (dart:async/future_impl.dart:51:12)
#14 _AsyncAwaitCompleter.complete.<anonymous closure> (dart:async/runtime/libasync_patch.dart:33:20)
#15 _rootRun (dart:async/zone.dart:1124:13)
#16 _CustomZone.run (dart:async/zone.dart:1021:19)
#17 _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:947:23)
#18 _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
#19 _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
#20 _runPendingImmediateCallback (dart:isolate/runtime/libisolate_patch.dart:115:13) …