Bridge Service hangs forever if invalid experiment file loaded

[ANeaves]

If the user attempts to load an experiment file that connects to a physical spectrometer, when that spectrometer is unpowered or otherwise disconnected, the bridge service will hang forever without feedback.

This is because, when run as a visible GUI, lightfield attempts to show a popup warning the user that the desired hardware is unavailable. However, as lightfield is not visible when run via the windows service, this popup message can never be cleared, and thus the issue never resolved.