Flutter

I find out why, the lantern VPN set the proxy for terminal

> https_proxy=[http://127.0.0.1:42117/](http://127.0.0.1:42117/)
> http_proxy=[http://127.0.0.1:42117/](http://127.0.0.1:42117/)
> no_proxy=localhost,127.0.0.0/8,::1

After unset these proxy, it runs well

发生如下报错，解决方式如上:

~/flutter_app$ flutter build apk
Running "flutter packages get" in flutter_app...
The setter 'readEventsEnabled=' was called on null.
Receiver: null
Tried calling: readEventsEnabled=false
package:pub/src/source/hosted.dart 344                                                   BoundHostedSource._throwFriendlyError
package:pub/src/source/hosted.dart 144                                                   BoundHostedSource.doGetVersions
===== asynchronous gap ===========================
package:pub/src/source.dart 168                                                          BoundSource.getVersions
package:pub/src/solver/package_lister.dart 77                                            PackageLister._versions.<fn>.<fn>
dart:async                                                                               runZoned
package:pub/src/http.dart 274                                                            withDependencyType
package:pub/src/solver/package_lister.dart 76                                            PackageLister._versions.<fn>
===== asynchronous gap ===========================
dart:async                                                                               new Future.sync
package:async/src/async_memoizer.dart 43                                                 AsyncMemoizer.runOnce
package:pub/src/solver/package_lister.dart 75                                            PackageLister._versions
package:pub/src/solver/package_lister.dart 112                                           PackageLister.countVersions
===== asynchronous gap ===========================
package:pub/src/solver/version_solver.dart 377                                           VersionSolver._choosePackageVersion.<fn>
===== asynchronous gap ===========================
package:pub/src/utils.dart 351                                                           minByAsync
===== asynchronous gap ===========================
package:pub/src/solver/version_solver.dart 373                                           VersionSolver._choosePackageVersion
===== asynchronous gap ===========================
package:pub/src/solver/version_solver.dart 120                                           VersionSolver.solve
===== asynchronous gap ===========================
package:pub/src/solver.dart 35                                                           resolveVersions.<fn>
package:pub/src/log.dart 409                                                             progress
package:pub/src/solver.dart 32                                                           resolveVersions
package:pub/src/entrypoint.dart 207                                                      Entrypoint.acquireDependencies
===== asynchronous gap ===========================
package:pub/src/command/get.dart 38                                                      GetCommand.run
package:args/command_runner.dart 194                                                     CommandRunner.runCommand
===== asynchronous gap ===========================
package:pub/src/command_runner.dart 168                                                  PubCommandRunner.runCommand.<fn>
dart:async                                                                               new Future.sync
package:pub/src/utils.dart 116                                                           captureErrors.<fn>
dart:async                                                                               runZoned
package:pub/src/utils.dart 135                                                           captureErrors
package:pub/src/command_runner.dart 168                                                  PubCommandRunner.runCommand
===== asynchronous gap ===========================
package:pub/src/command_runner.dart 117                                                  PubCommandRunner.run
===== asynchronous gap ===========================
/b/build/slave/Mac_Engine/build/src/third_party/dart/third_party/pkg/pub/bin/pub.dart 8  main
This is an unexpected error. Please run

    pub --trace --verbosity=warning get --no-precompile

and include the logs in an issue on https://github.com/dart-lang/pub/issues/new
pub get failed (1)