flutter doctor で ideviceinfo のエラーが出る場合

以下のようなエラーがでた。

```
~: flutter doctor -v
[✓] Flutter (Channel dev, v1.2.1, on Mac OS X 10.14.2 18C54, locale ja-JP)
    • Flutter version 1.2.1 at /Applications/flutter
    • Framework revision 8661d8aecd (6 days ago), 2019-02-14 19:19:53 -0800
    • Engine revision 3757390fa4
    • Dart version 2.1.2 (build 2.1.2-dev.0.0 0a7dcf17eb)

⣻Unhandled exception:
Exception: ideviceinfo returned an error:
ERROR: Could not connect to lockdownd, error code -19

#0      IMobileDevice.getInfoForDevice (package:flutter_tools/src/ios/mac.dart:141:9)
<asynchronous suspension>
#1      IOSDevice.getAttachedDevices (package:flutter_tools/src/ios/devices.dart:156:55)
<asynchronous suspension>
#2      IOSDevices.pollingGetDevices (package:flutter_tools/src/ios/devices.dart:110:57)
#3      PollingDeviceDiscovery.devices (package:flutter_tools/src/device.dart:171:52)
<asynchronous suspension>
#4      DeviceManager.getAllConnectedDevices (package:flutter_tools/src/device.dart:99:46)
<asynchronous suspension>
#5      DeviceValidator.validate (package:flutter_tools/src/doctor.dart:694:54)
<asynchronous suspension>
#6      Doctor.startValidatorTasks (package:flutter_tools/src/doctor.dart:116:52)
#7      Doctor.diagnose (package:flutter_tools/src/doctor.dart:189:41)
#8      _AsyncAwaitCompleter.start (dart:async/runtime/libasync_patch.dart:49:6)
#9      Doctor.diagnose (package:flutter_tools/src/doctor.dart:179:24)
#10     DoctorCommand.runCommand (package:flutter_tools/src/commands/doctor.dart:48:39)
#11     _AsyncAwaitCompleter.start (dart:async/runtime/libasync_patch.dart:49:6)
#12     DoctorCommand.runCommand (package:flutter_tools/src/commands/doctor.dart:34:42)
#13     FlutterCommand.verifyThenRunCommand (package:flutter_tools/src/runner/flutter_command.dart:545:18)
#14     _asyncThenWrapperHelper.<anonymous closure> (dart:async/runtime/libasync_patch.dart:77:64)
#15     _rootRunUnary (dart:async/zone.dart:1132:38)
#16     _CustomZone.runUnary (dart:async/zone.dart:1029:19)
#17     _FutureListener.handleValue (dart:async/future_impl.dart:126:18)
#18     Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:639:45)
#19     Future._propagateToListeners (dart:async/future_impl.dart:668:32)
#20     Future._complete (dart:async/future_impl.dart:473:7)
#21     _SyncCompleter.complete (dart:async/future_impl.dart:51:12)
#22     _AsyncAwaitCompleter.complete.<anonymous closure> (dart:async/runtime/libasync_patch.dart:33:20)
#23     _rootRun (dart:async/zone.dart:1124:13)
#24     _CustomZone.run (dart:async/zone.dart:1021:19)
#25     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:947:23)
#26     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
#27     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
#28     _runPendingImmediateCallback (dart:isolate/runtime/libisolate_patch.dart:115:13)
#29     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:172:5)
```

ideviceinfo のコマンド単独で失敗する。

```
~: ideviceinfo
ERROR: Could not connect to lockdownd, error code -19
```

以下のように、ideviceinstallerを削除して再インストールしたら解決した。

```
brew update
brew uninstall --ignore-dependencies libimobiledevice
brew uninstall --ignore-dependencies usbmuxd
brew install --HEAD usbmuxd
brew unlink usbmuxd
brew link usbmuxd
brew install --HEAD libimobiledevice
brew install ideviceinstaller
```

なお、単に usbmuxd を kill すればよいという[説もみかけた](https://github.com/flutter/flutter/issues/23455#issuecomment-450832142)。

```
sudo pkill usbmuxd
```