[llvm] [MachO] Replace getStruct with getStructOrErr (PR #95810)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

Please don't force push to PRs, per the LLVM PR policy. If you need to rebase, you can use a merge commit to merge the latest changes into your PR branch. Using a force push trashes the review history, making it impossible to easily see what has changed from the previous version.

https://github.com/llvm/llvm-project/pull/95810