fix: misleading error message when git is not installed

[ZachDreamZ]

The checkGitRepo() function was catching all execSync failures uniformly. When git is not installed, the error has code: 'ENOENT' with empty stderr, producing the misleading "Not a git repository" message instead of telling the user git is missing.

Added an ENOENT check so users see "git is not installed or not found on PATH" when git is missing. The existing fallback for non-git directories (stderr from git rev-parse --git-dir) is preserved.

Fixes #185

Summary by CodeRabbit

• Bug Fixes
  • Improved git repository checks to return clearer error messages when Git is missing or unavailable on the system PATH.
  • Made repository validation errors more reliable by using the available error output when present, with a clearer fallback message for non-git directories.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between c4a0195 and b95cd62.

📒 Files selected for processing (1)

• src/git/diff.ts

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🧰 Additional context used

📓 Path-based instructions (2)

src/**/*.ts

📄 CodeRabbit inference engine (AGENTS.md)

The project is ESM-only: use .js extensions in local imports and keep verbatimModuleSyntax-compatible TypeScript imports (for example, import type for type-only imports).

Files:

• src/git/diff.ts

src/git/**/*.ts

📄 CodeRabbit inference engine (AGENTS.md)

Git operations should use execSync/spawnSync rather than simple-git; diff buffering must stay within the 100MB limit, and commits should use temp files via git commit -F.

Files:

• src/git/diff.ts

🪛 ast-grep (0.44.0)

src/git/diff.ts

[warning] Importing child_process exposes a command-execution surface; ensure any command/argument built from input is validated, and prefer execFile/spawn with an argument array over exec.
Context: import { execSync, spawnSync } from 'node:child_process';
Note: [CWE-78] Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection').

(detect-child-process-typescript)

🔇 Additional comments (1)

src/git/diff.ts (1)

20-31: LGTM!

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📝 Walkthrough

Walkthrough

Updated the checkGitRepo function's error handling in src/git/diff.ts to detect when the git executable is missing (ENOENT) and throw a specific message, while retaining stderr-based error messages for other failures.

Changes

Error Handling Fix

Layer / File(s)	Summary
Distinguish missing git from other repo errors src/git/diff.ts	checkGitRepo now casts the caught error to NodeJS.ErrnoException, checks for err.code === 'ENOENT' to throw "git is not installed or not found on PATH", and otherwise derives stderr from the error for the existing fallback message.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Poem

A hop, a check, a git-dir quest,
No PATH found? I throw my best:
"Not installed!" I clearly say,
No more confusion leads astray.
🐇 Thump, thump — bug fixed today!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main fix for git-missing error handling and is concise.
Linked Issues check	✅ Passed	The change matches issue #185 by handling ENOENT separately and preserving the not-a-repo fallback.
Out of Scope Changes check	✅ Passed	The PR is narrowly scoped to checkGitRepo error handling and adds no unrelated changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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Thanks, LGTM!