[bug?] git diff --cached in a non-git directory

Thank you for filling out a Git bug report! Please answer the following questions to help us understand your issue.

What did you do before the bug happened? (Steps to reproduce your issue) I changed into a non-git directory. Then I called git with 'git diff --cached', which produced this error:

error: unknown option `cached' usage: git diff --no-index [<options>] <path> <path> [...]

What did you expect to happen? (Expected behavior) A helfpul error message.

What happened instead? (Actual behavior) An unhelpful error message saying that cached is an unknown option.

What's different between what you expected and what actually happened? Me being confused why git suddenly forgot that `git diff --cached` is an allowed option.

Anything else you want to add: Please fix and thank you for this great tool!

Please review the rest of the bug report below. You can delete any lines you don't wish to share.

[System Info] git version: git version 2.46.0 cpu: arm64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 shell-path: /bin/sh feature: fsmonitor--daemon libcurl: 8.4.0 zlib: 1.2.12 uname: Darwin 23.6.0 Darwin Kernel Version 23.6.0: Mon Jul 29 21:14:21 PDT 2024; root:xnu-10063.141.2~1/RELEASE_ARM64_T8103 arm64 compiler info: clang: 15.0.0 (clang-1500.3.9.4) libc info: no libc information available $SHELL (typically, interactive shell): /opt/homebrew/bin/bash

[Enabled Hooks] not run from a git repository - no hooks to show