fix: recover handling of typing.Optional[X] (#90)
This fixes downstream bug
https://github.com/bouweandela/snakemake-storage-plugin-rucio/issues/41
which prevented type.Optional[int] settings from performing a type
conversion.
Turns out that was a regression from
https://github.com/snakemake/snakemake-interface-common/pull/59
@jjjermiah
typing.Union[X] is not instance of type. The logic of the function is
about checking the type of value, so specifying a narrow annotation
forces duplicating function logic around its calls.

Summary by CodeRabbit

Bug Fixes

Improved error handling for type conversions in plugin settings with
clearer, descriptive user-facing errors when conversion fails.

Refactor

Broadened plugin type handling to accept more complex type
representations and enforce valid Union usage (disallowing non-Optional
unions).

Tests

Added tests covering integer conversion and Optional[int] handling for
plugin settings, plus example plugin/settings scaffolding.



Co-authored-by: aider (anthropic/claude-sonnet-4-20250514) aider@aider.chat
Co-authored-by: Johannes Köster johannes.koester@uni-due.de