What is causing python nested exception error in VS Code with Click command line processor?

[jules43]

I am using Click with Python 3.10.4 on Windows with VS Code. I have this simple test program:

import click

@click.group()
async def cli():
    click.echo("cli()")

@cli.command()
@click.argument('ip')
async def monitor(ip: str):
    click.echo("monitor()")

if __name__ == "__main__":
    cli()

If I run this with "python test.py monitor" it exits with an error saying missing IP argument, which is what I'd expect.

When I run it in the debugger (debugpy) within VS Code with the same command line, it comes up with the following message:

Exception has occurred: System Exit
2
During handling of above exception, another exception occurred

And points to the last line of code (cli())

I'm fairly new to Python and trying to understand if this is expected. It appears to be saying that while processing SystemExit exception another exception occurred.

I'm not sure if this is a feature of Click, a bug in my code or just expected behaviour.

I'd like it to just finish without an uncaught exception as this doesn't seem to give me any useful information, or the ability to diagnnose the problem. Is there a way to handle this more gracefully?

[jules43]

I found a way to get a bit more information about the nested exceptions, but I'm not sure how to interpret it:

Exception has occurred: SystemExit (note: full exception trace is shown but execution is paused at: )
2
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 1053, in main
rv = self.invoke(ctx)
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 1653, in invoke
cmd_name, cmd, args = self.resolve_command(ctx, args)
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 1717, in resolve_command
ctx.fail(_("No such command {name!r}.").format(name=original_cmd_name))
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 673, in fail
raise UsageError(message, self)

During handling of the above exception, another exception occurred:

File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 673, in fail
raise UsageError(message, self)
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 1717, in resolve_command
ctx.fail(_("No such command {name!r}.").format(name=original_cmd_name))
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 1653, in invoke
cmd_name, cmd, args = self.resolve_command(ctx, args)
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 1053, in main
rv = self.invoke(ctx)
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 1071, in main
sys.exit(e.exit_code)
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\site-packages\click\core.py", line 1128, in call
return self.main(*args, **kwargs)
File "C:\Users\jphda\OneDrive\Documents\PythonDev\Kasa\test2.py", line 22, in (Current frame)
cli()
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\runpy.py", line 86, in _run_code
exec(code, run_globals)
File "C:\Users\jphda\miniconda3\envs\Kasa\Lib\runpy.py", line 196, in _run_module_as_main
return _run_code(code, main_globals, None,