flutter camera: Error clearing streaming request: Function not implemented - flutter

Question

I am working on an app in flutter that uses the camera.
I have followed the basic flutter tutorial
https://flutter.dev/docs/cookbook/plugins/picture-using-camera
However, when I am on a screen using the CameraPreview widget, and I navigate to another app that uses the camera, like snapchat, I see the following error when opening snapchat (the error comes from my app), has anyone else seen this before?
Returning to my app shows the camera in a frozen/paused state.
I/CameraManagerGlobal(30470): Camera 0 facing CAMERA_FACING_BACK state now CAMERA_STATE_IDLE for client com.my.cliet API Level 2
I/CameraManagerGlobal(30470): Camera 0 facing CAMERA_FACING_BACK state now CAMERA_STATE_CLOSED for client com.my.cliet API Level 2
E/CameraCaptureSession(30470): Session 0: Exception while stopping repeating:
E/CameraCaptureSession(30470): android.hardware.camera2.CameraAccessException: CAMERA_ERROR (3): cancelRequest:547: Camera 0: Error clearing streaming request: Function not implemented (-38)
E/CameraCaptureSession(30470): at android.hardware.camera2.CameraManager.throwAsPublicException(CameraManager.java:1340)
E/CameraCaptureSession(30470): at android.hardware.camera2.impl.ICameraDeviceUserWrapper.cancelRequest(ICameraDeviceUserWrapper.java:99)
E/CameraCaptureSession(30470): at android.hardware.camera2.impl.CameraDeviceImpl.stopRepeating(CameraDeviceImpl.java:1259)
E/CameraCaptureSession(30470): at android.hardware.camera2.impl.CameraCaptureSessionImpl.close(CameraCaptureSessionImpl.java:578)
E/CameraCaptureSession(30470): at android.hardware.camera2.impl.CameraCaptureSessionImpl$2.onDisconnected(CameraCaptureSessionImpl.java:789)
E/CameraCaptureSession(30470): at android.hardware.camera2.impl.CameraDeviceImpl$7.run(CameraDeviceImpl.java:245)
E/CameraCaptureSession(30470): at android.os.Handler.handleCallback(Handler.java:938)
E/CameraCaptureSession(30470): at android.os.Handler.dispatchMessage(Handler.java:99)
E/CameraCaptureSession(30470): at android.os.Looper.loop(Looper.java:246)
E/CameraCaptureSession(30470): at android.app.ActivityThread.main(ActivityThread.java:8506)
E/CameraCaptureSession(30470): at java.lang.reflect.Method.invoke(Native Method)
E/CameraCaptureSession(30470): at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
E/CameraCaptureSession(30470): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)
E/CameraCaptureSession(30470): Caused by: android.os.ServiceSpecificException: cancelRequest:547: Camera 0: Error clearing streaming request: Function not implemented (-38) (code 10)
E/CameraCaptureSession(30470): at android.os.Parcel.createExceptionOrNull(Parcel.java:2399)
E/CameraCaptureSession(30470): at android.os.Parcel.createException(Parcel.java:2369)
E/CameraCaptureSession(30470): at android.os.Parcel.readException(Parcel.java:2352)
E/CameraCaptureSession(30470): at android.os.Parcel.readException(Parcel.java:2294)
E/CameraCaptureSession(30470): at android.hardware.camera2.ICameraDeviceUser$Stub$Proxy.cancelRequest(ICameraDeviceUser.java:750)
E/CameraCaptureSession(30470): at android.hardware.camera2.impl.ICameraDeviceUserWrapper.cancelRequest(ICameraDeviceUserWrapper.java:97)
E/CameraCaptureSession(30470): ... 11 more

Answer 1

So I have resolved the issue by adding the following which aren't included in the link that I posted.
in the initState() method I had to manually add the observer
WidgetsBinding.instance!.addObserver(this);
I had to define/modify the didChangeAppLifecycleState(...) function as follows
#override
void didChangeAppLifecycleState(AppLifecycleState state) {
final CameraController? cameraController = _controller;
// App state changed before we got the chance to initialize.
if (cameraController == null || !cameraController.value.isInitialized) {
return;
}
if (state == AppLifecycleState.inactive) {
cameraController.dispose();
} else if (state == AppLifecycleState.resumed) {
this._controller = CameraController(
widget.camera,
ResolutionPreset.medium,
);
if (mounted) {
setState(() {
this._initializeControllerFuture = this._controller.initialize();
});
}
}
}