I tried MultiConnect (on 1.16.3) with custom server using node-minecraft-protocol (1.16.1) as a base and got this error.

Vanilla 1.16.1 works just fine with it

Log: https://gist.github.com/Patbox/370316b0d158ec268fd6016a8dcfe0e4

Server: pb4.eu:25566
Server software:

• VoxelSrv-Server
• MConnect (plugin for Minecraft protocol)
• MC Protocol Lib I used (with selected version 1.16.1):

Oh no, it's that code... I was wondering when that would break on someone...