Improve Error & Warning Handling

[Lukas113]

We could/should improve the Karabo error and warning handling. What I mean by that is the following:

Error-Handling

• For errors we throw, we should always use custom errors. The reason is because if someone wants to do proper error-handling on their side, we would make it much easier for them. They could just e.g. catch KaraboError (or any inherited error from KaraboError) to just handle errors we throw. However, we also should also follow the Python built-in exception specification. Therefore I suggest the following error-structure, which inherit always from KaraboError and the according built-in exception:

class KaraboError(Exception): ...

class KaraboRuntimeError(KaraboError, RuntimeError): ...

class KaraboValueError(KaraboError, ValueError): ...

class MaybeAnEvenMoreSpecificError(KaraboRuntimeError): ...

# other exceptions

Waring-Handling

• For warnings, we should also use custom warnings. This makes it way easier for a third-party user to ignore karabo-specific warnings without ignoring other warnings of the same kind. The inheritance structure is the same as for exceptions:

class KaraboWarning(Warning): ...

class KaraboUserWarning(KaraboWarning, UserWarning): ...

class KaraboFutureWarning(KaraboWarning, FutureWarning): ...

class MaybeAnEvenMoreSpecificWarning(KaraboUserWarning): ...

This specific approach would enhance the error and warning handling possibilities for a third-party user by a lot. The only requirement for us to just throw KaraboError (inherited) and use KaraboWarning (inherited).