Exception raised when qdarkstyle is not installed

[wshanks]

It looks like this code is intended to make qdarkstyle optional by catching the import error exception, but then it calls qdarkstyle.load_stylesheet() any way:

https://github.com/Qiskit/qiskit-metal/blob/171fa3c0fa5309c89ad6b93ef21f3dd9c6eeb758/qiskit_metal/_gui/main_window_base.py#L525-L535

[zlatko-minev]

Maybe @dwang429 or @grace-harper-ibm can handle this? just default stylesheet. Actually, I think the default should now be the custom one i wrote based on qdarkstyle.

[priti-ashvin-shah-ibm]

qdarkstyle is a dependency which now is within environment.yml.

We an close this.