Granting permission using camera package pauses the debugger on an exception

May be the actual culprit is didChangeAppLifecycleState.

Once you call await _controller.initialize(); and the permission dialog is shown, the lifecycle event AppLifecycleState.inactive is triggered and current controller is disposed as per your code in didChangeAppLifecycleState, hence when the application resumes after permissions given and tries to continue, it throws error.

Try removing

if (state == AppLifecycleState.inactive) {  _controller?.dispose();}

Or have a local variable to check if initializing and ignore dispose when initiliazing like

Future<void> _initialize() async {  await _getCameras();  _controller = CameraController(_availableCameras[0], ResolutionPreset.high);  _initializing = true;  await _controller.initialize();  _initializing = false;  if (!mounted) {    return;  }  setState(() {});}

and in didChangeAppLifecycleState

if (state == AppLifecycleState.inactive && !_initializing) {  _controller?.dispose();}

EDIT:

May be, I think I found the issue, the actual issue is didChangeAppLifecycleState as expected, the if clause in the didChangeAppLifecycleState, if it truns out to be true, _controller is being disposed, if not _setCurrentCamera is just disposing any active controller. Hence when you invoke initialize and wait for permissions, before permission future resolves, the _controller is being disposed by didChangeAppLifecycleState.

My solution would work with simple change. Change your initState to

@overridevoid initState() {  super.initState();  _initializing = true; // set to true  WidgetsBinding.instance.addObserver(this);  _initialize();}

change your _initialize function to make _initializing = false after intializing like,

Future<void> _initialize() async {  await _getCameras();  _controller = CameraController(_availableCameras[0],ResolutionPreset.high);  await _controller.initialize();  _initializing = false; // set to false  if (!mounted) {    return;  }  setState(() {});}

and your didChangeAppLifecycleState to

@overridevoid didChangeAppLifecycleState(AppLifecycleState state) {  if(_initializing){    return;  }  if (state == AppLifecycleState.inactive) {    _controller?.dispose();  } else if (state == AppLifecycleState.resumed) {    if (_controller != null) {      _setCurrentCamera(_controller.description);    }  }}

This way, if _initializing == true you never dispose the current controller.

Hope that helps!