fix: address PR #2 review feedback

[chiply]

Summary

• Assert stringp return from brushup--eval-style on error (the message call in the condition-case handler returns a string, not nil)
• Replace || true on eask install-deps with exit-code-2-specific handling so real dependency resolution failures fail the job clearly (exit 2 = no deps to install, which is expected)
• Add inline comments explaining the Nix cache steps are needed because jcs090218/setup-emacs uses Nix to install Emacs on Linux

Review items addressed

• feat: add ERT tests, CI optimizations, and release-please improvements #2 comment on test/brushup-test.el:78 (handles-error assertion)
• feat: add ERT tests, CI optimizations, and release-please improvements #2 comment on ci.yml:53,86 (|| true masking failures)
• feat: add ERT tests, CI optimizations, and release-please improvements #2 comment on ci.yml:34,67 (Nix cache explanation)

Items already resolved in prior commits: lexical binding for eval-style and brushup-test--marker (both use defvar).

Test plan

• CI passes on all matrix jobs (exit code handling works cross-platform)
• handles-error test still passes with stringp assertion

Generated with Claude Code

[Copilot]

Pull request overview

This PR addresses review feedback from PR #2, focusing on three specific improvements: better test coverage for error handling, more robust CI dependency installation, and explanatory comments for Nix cache usage.

Changes:

• Enhanced error handling test for brushup--eval-style to verify it returns a string message instead of just not signaling
• Replaced || true with proper exit code handling for eask install-deps to allow exit code 2 (no dependencies) while failing on actual errors
• Added inline comments explaining Nix cache steps are needed because jcs090218/setup-emacs uses Nix on Linux

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
test/brushup-test.el	Added stringp assertion to verify error handler returns a message string
.github/workflows/ci.yml	Improved CI robustness with proper exit code handling and added explanatory comments for Nix cache

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[Copilot]

The shell: bash directive is missing in the lint job's "Install dependencies" step, but it's present in the test job's equivalent step (line 52). This inconsistency could cause portability issues since the bash-specific syntax ([ ... ] || [ ... ] || exit ...) is used in the run script. While ubuntu-latest defaults to bash, it's better to be explicit for consistency and clarity.

Suggested change

	- name: Install dependencies
	- name: Install dependencies
	shell: bash