Flutter 导包错误 Target of URI doesn

https://flutter.io/using-packages/ 官方教程

Stop and restart the app, if necessary
If the package brings platform-specific code (Java/Kotlin for Android, Swift/Objective-C for iOS), that code must be built into your app. Hot reload and hot restart do this only for the Dart code of the package, so you may have to do a full restart of the app to avoid errors like MissingPluginException when using the package.

如果出现丢包错误，重新启动编译器。这里我用的vscode。