User defined exceptions show as Unknown in redun console

[tesujimath]

Actually, it's not all user defined exceptions which do this. It's any exception class for which the constructor has multiple required parameters.

I fixed it in my case by defining default values for all but the first parameter in the constructor for the exception. Like this:

class MyCalledProcessError(Exception):
    def __init__(self, stderr: str | bytes, returncode: int = 0, cmd: List[str] = []):
        """To avoid showing as Unknown in redun console, the constructor must have only one parameter without default value."""
        self.stderr = stderr
        self.returncode = returncode
        self.cmd = cmd
        super().__init__(str(self))

My guess is that deserializing the exception from the redun database for use in the console is failing because it tries to create the exception object with only a single parameter before populating the rest. But that is a guess, I didn't have a close look at how that works.

If it is fixable that would be great. Otherwise this issue can help others who stumble over the same behaviour.