Issue Description:

Note: If this bug occurs in a modpack, please report this to the modpack author.

Almost identical to #3895. Just providing another data point.

What happens:

Single-player server crashes, but the single-player client does not crash.

What you expected to happen:

No crashes.

Steps to reproduce:

1. Play Single Player.
2. Set useSneakMouseWheelYetaWrench to false in configuration via in-game "Mod Options" with Apply Globally checked.
3. Whilst playing, press the Yeta config key Y.

Affected Versions (Do not use "latest"):

• EnderIO: EnderIO-1.7.10-2.3.0.429_beta
• EnderCore: EnderCore-1.7.10-0.2.0.39_beta
• Minecraft: 1.7.10
• Forge: forge-10.13.4.1614

Your most recent log file where the issue was present:

https://gist.github.com/Psithief/aea942f97960c3b8ac5200fc1c54fc5c

A known good version

• EnderIO: EnderIO-1.7.10-2.3.0.423_beta
• EnderCore: EnderCore-1.7.10-0.2.0.31_beta
• Minecraft: 1.7.10
• Forge: forge-10.13.4.1558

Closing temporarily, will re-open if modpack author can't fix.

I gotta build my own version 👍

As soon as I figure out what the last build was built from. Oh right. branch master is 1.7.10 and branch 1.10 is what's current.

Yes, I think this is the same cause, just another way to trigger an error from it. In that other case, client and server couldn't agree about network packets because the server knew one more than the client, in this case that "unused" network packet is actually used from somewhere else.

Is there a last known good version between those two versions listed?

That problem most likely has existed for ages, so no known good version...