Error 422 when send an custom Warning message to an User.

[DasMuelli]

Steps to reproduce the problem

1. Login as Admin
2. Open an Report and send an custom Warning Message to the User.
3. Send message
4. Page open with error 422 Error.

Expected behaviour

Successfully send an Warning Message to the User.

Actual behaviour

Error message when I would send an Warning Message to the User.

Detailed description

When I dial into my instance as an administrator. Go to the menu there and want to edit a message from a user, and finally want to give a warning to the user this mistake.

Specifications

Mastodon 4.0.2 Nginx reverse Proxy Docker-compose setup Debian system