GitLab MergeRequest API (diffs endpoint) returns 500 internal server error when per_page parameter is set

Summary

Calls to MergeRequest's diff endpoint fail if you set the per_page Parameter. Response code is 500 - Internal Server error

Steps to reproduce

https://gitlab.example.com/api/v4/projects/:projectID/merge_requests/::mergeRequestIID/diffs?per_page=

Example Project

N/A, it's the API

What is the current bug behavior?

{"message":"500 Internal Server Error"}

What is the expected correct behavior?

[{"diff": <your Diff>,"new_path": ... }, ... nth element]

Relevant logs and/or screenshots

Gitlab API Error.postman_collection.json

Output of checks

I'm using Gitlab's SaaS.

#427155 (closed)