Crash: USB screen starts its service while the app counts as in the background #189

Crash reported in the Play Console:

android.app.BackgroundServiceStartNotAllowedException
  at android.content.ContextWrapper.startService
  at in.co.gorest.grblcontroller.UsbConnectionActivity.onStart (UsbConnectionActivity.java:82)

Cause

UsbConnectionActivity.onStart() calls startService() for GrblUsbSerialService. Android refuses a service start while it counts the app as in the background, and it can do that at the first onStart() (for example when the screen turns off as the activity starts). The refusal is not caught, so the app crashes.

The service is already created and kept alive by bindService() in onCreate(), and its onStartCommand() does nothing, so the start can be skipped when Android refuses it.

Fix

Catch IllegalStateException around that startService() call and log a warning. BackgroundServiceStartNotAllowedException (Android 12+) and the older refusal both extend it.

Acceptance

• When Android refuses the start, the app logs a warning and does not crash. USB connect still works through the bound service.
• When Android allows the start, nothing changes.