283 fix(discovery): don't crash when an optional dependency (e.g. matplotlib) is missing

[Gnpd]

Summary

all_estimators(), all_displays(), and all_functions() crashed with an uncaught ImportError whenever matplotlib (the viz extra) wasn't installed, since chemotools.plotting/chemotools.inspector fail to import without it and discovery had no handling for that.

This is a fast fix for the immediate crash, but it's also worth keeping as a general safeguard: any future subpackage with an optional dependency will now degrade gracefully instead of breaking discovery for everyone.

Fixes #283.

Changes

• Extract a shared _iter_chemotools_modules() generator (used by all three public functions) that catches ImportError per submodule and emits a UserWarning naming the skipped module instead of propagating, a permanent safeguard, not just a one-off patch, so any future optional-dependency-gated subpackage degrades gracefully instead of crashing discovery.
• Warning is raised with stacklevel=3 so it's attributed to the caller's own call site (e.g. their all_estimators() call) rather than to internal discovery-loop plumbing.
• Add a regression test (test_discovery_skips_module_with_missing_optional_dependency) that fakes an ImportError from chemotools.plotting/chemotools.inspector to simulate matplotlib being absent, and asserts each discovery function still returns a list and warns instead of crashing.

[Copilot]

Pull request overview

This PR hardens chemotools.utils.discovery so all_estimators(), all_displays(), and all_functions() no longer crash when importing a subpackage fails due to a missing optional dependency (e.g. matplotlib for viz), and instead skip the failing module with a warning.

Changes:

• Add _iter_chemotools_modules() to centralize module iteration and handle per-module ImportError by warning and skipping.
• Update all_estimators(), all_displays(), and all_functions() to use the shared iterator.
• Add a regression test ensuring discovery warns and still returns a list when chemotools.plotting / chemotools.inspector can’t be imported.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
chemotools/utils/discovery.py	Introduces a shared module iterator that catches ImportError during discovery and updates all discovery entrypoints to use it.
tests/utils/test_discovery.py	Adds a regression test that simulates an ImportError from optional-dependency-gated subpackages and asserts discovery warns instead of crashing.

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[Gnpd]

stacklevel=3 is already correct

Tested directly, by calling all_estimators() from a notebook cell with a submodule forced to fail import:

stacklevel=3 (current):
...ipykernel_15920\875199054.py:21: Skipping 'chemotools.plotting' during discovery: ...
→ line 21 is the exact cell line that called all_estimators(). Correct.

stacklevel=4 (proposed):
...IPython\core\interactiveshell.py:3546: Skipping 'chemotools.plotting' during discovery: ...
→ overshoots past the caller entirely, into IPython's own cell-execution internals.

So stacklevel=4 is strictly worse, not a fix. Keeping stacklevel=3 as-is.