The crash! macro is a leftover from old error handling in this project. We should always use UError and show! now.

Here are all uses of crash!: https://github.com/search?q=repo%3Auutils%2Fcoreutils%20crash!&type=code

We can tackle each of these in separate PRs. Make sure not to link those PRs to this issue (so don't write "closes #XXXX"), because that might close it prematurely. Only I've started here: https://github.com/search?q=repo%3Auutils%2Fcoreutils%20crash!&type=code

This is a good first issue if you're looking for one!