[Bug] Holding hub buttons while starting programs gives error

[laurensvalk]

Describe the bug Running a program while holding the hub buttons raises an unexpected error:

To reproduce Keep holding the left or right button and try to start a program or the REPL.

Expected behavior It is intentional that a program cannot be started in some states, but we need to handle this better.

We can adjust the Hub UI to give Pybricks Code actions priority and start the program even if buttons are held, or inform the user about it in Pybricks Code (but I don't know if we can make this error type that specific).