Maybe this question is repeated but I couldn't find anything.
Let's suppose I'm developing with ruby and I'm debugging a file with byebug, so in that file I have the word "byebug".
I find the problem and save that correct file but I forget to remove the byebug word. so when I commit that file, it will be commited with that word, than can cause in production the app not working well.
I'm using magit and emacs, so before committing I always can read the diff and look for the "byebug" word. If there it is I can remove.
I also know that I can do something similar to
git diff | grep byebug
What you are looking for is called Git hooks. Hooks are scripts that are run at different stages (pre-commit, post-commit) and can prevent the action to succeed.
I think that in your case the client-side pre-commit hook is what you are looking for. An useful introduction to git hooks https://www.digitalocean.com/community/tutorials/how-to-use-git-hooks-to-automate-development-and-deployment-tasks