Error 2003332927 when accessing AVCaptureDevice?

Can anyone tell me what error 2003332927 means? I am getting this when trying to connect to my UVC based slide scanner, but I can't find any good indicating what the code means and what the suggested resolution method is? BTW it has worked on previous occasions.

A sample of the code in question:

Code Block swift
     let device: AVCaptureDevice = self.devices[defaultDevice];
     
    if (captureSession != nil) {
      /* if we are "restarting" a session but the device is the same exit early */
      let currentDevice = (self.captureSession.inputs[0] as! AVCaptureDeviceInput).device
      guard currentDevice != device else { return }
       
      captureSession.stopRunning();
    }
    captureSession = AVCaptureSession();
     
    do {
       self.input = try AVCaptureDeviceInput(device: device);
       self.captureLayer = AVCaptureVideoPreviewLayer(session: self.captureSession);
      self.captureSession.addInput(input);
      self.captureSession.startRunning();
      self.captureLayer = AVCaptureVideoPreviewLayer(session: self.captureSession);
       // other code here
   } catch {
      // catch logic here
   }

The following line is where we first see the error logged in the console:

Code Block swift
self.captureLayer = AVCaptureVideoPreviewLayer(session: self.captureSession);

I am trying to work out if there is an initialisation or parameter missing? Or maybe the issue is closer to the device, but I still need to know the significance of the error to better communicate to the user how to deal with this.

BTW checking the status of the device:

Code Block 
NSLog(String(device.isSuspended)); // result: false
NSLog(String(device.isInUseByAnotherApplication)); // result: false
NSLog(String(device.isConnected)); // result: true

Project Context: https://github.com/simonguest/quick-camera