Commenting on articles will result in an error
## Summary
When posting a comment on an article there will be "Failed to load resource: the server responded with a status of 500 (Internal Server Error)"
Steps to reproduce
1. navigate to https://test.conduit.wimmalab.org
2. log in
3. click on Global Feed
4. click on any article headline
5. fill textbox "Write a comment..." with some text
6. click "Post Comment"
## What is the current bug behavior?
A blank page shows
The javascript console says 500 Internal Server Error
## What is the expected correct behavior?
The comment should appear below the article
## Relevant logs and/or screenshots

## Possible fixes
Fix the react javascripts
## Testing
[X] Commenting on article went trough successful and didn't cause an error. Tester: @AB0197
issue