Crash: Named Enderdragon seems to have crashed me

This ticket is invalid as it relates to a modified or 3rd party client, server, or launcher.

• Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.

• Any plugin issues need to be addressed to the creator of the plugin or resource pack.

• This site is for addressing issues related to the base unmodded Minecraft; Bukkit, Forge, Optifine, or any other modded system invalidates your ticket, unless it can be shown to happen in Vanilla.

• Additionally, if you have problems on large-scale modded servers, please report it to their site. It's probably not a bug in Vanilla Minecraft.

Okay, because I joined with 100% vanilla 1.8.1-pre
and it caused me to crash. Not the server. Just my client. I am not sure why.
I don't crash in 1.8 btw. So it could be a vanilla bug. I just wanted to mention this. I reported it now to their site too: https://oc.tc/forums/topics/543ee0375f35b914a1001044

Edit: To their github too :https://github.com/OvercastNetwork/Issues/issues/1269

Yes, but the server is modded. That invalidates this ticket.

1.8.1-pre2 crash.

I am not sure why. But because the client isn't modded, shouldn't the client send me back to main menu with an error instead of crashing me anyways?
[Attachment Note]

The server is modded, it's an issue on their side.

Well fixed now. In pre-3