Describe the bug
When starting a Forge Server with Anvilclient on it it always crashes during startup.

To Reproduce

1. Put Anvilclient on a Forge Server
2. Start the server
3. Wait for the crash

System Info:

• Version: [e.g. 1.16.5-1.1.0.0]
• OS: [e.g. Windows 10]
• Java Version: [e.g. 1.8.0_271]

Additional context
Crash Report
crash-2021-06-02_13.54.32-fml.txt