Merge request diffs with submodules on same instance return 500 error

Summary

I opened an MR with very few (less than 1000) file changes, but the MR has a lot of file moves. I'm unable to load the changes tab in the MR. Network shows diff.js is failing with a 500 error.

Steps to reproduce

1. Create an MR with ~500 file moves
2. View Changes tab

Example Project

My project is private, but I can try to create a public reproduction if desired.

What is the current bug behavior?

The Changes tab never loads

What is the expected correct behavior?

The Changes tab loads.

Output of checks

this bug happens on gitlab.com