Unable to post comments on snippets

Summary

Clicking the submit button on the comment on a snippet takes forever.

Steps to reproduce

  1. Write a comment on a snippet.
  2. Click submit.
  3. It takes forever to submit.

Example Project

This bug can be reproduced on Debian Salsa running GitLab Community Edition 12.0.3

What is the current bug behavior?

Submit button stays clicked, but the comment never gets submitted.

What is the expected correct behavior?

The comment should be submitted on the snippet page.

Relevant logs and/or screenshots

image