fix: show full option name in error for invalid multi-char short options

[by22Jy]

Summary

• When a multi-character short option like -dbgwrong fails validation, the error message now shows the full option name instead of just the first character.

Context

Fixes #2779

Previously, when passing an invalid multi-character short option (e.g., -dbgwrong), the error would only show the first character:

No such option: -d

This was confusing because the user passed -dbgwrong, not -d.

Changes

Now the error correctly shows the full option name:

No such option: -dbgwrong

The fix captures the remaining characters when a short option fails to match and includes them in the error message.

Testing

Tested manually with a Click app:

import click

@click.command()
@click.option("-d", "--debug", is_flag=True)
def cli(debug):
    pass

if __name__ == "__main__":
    cli()

Running python test.py -dbgwrong now shows:

No such option: -dbgwrong