Server crashes during world load.
No crash report was generated so the server log has been provided instead.

java.lang.NoClassDefFoundError: net/minecraft/client/util/ITooltipFlag

Mod version: 1.8.19-B33
Forge version: 1.12-14.21.1.2387

Server log: gist/d90f6c739adf04155748734ca31d4851#L2184

Drunk told me I fixed this >.>