Crashing when I type

Put the summary of the bug you're having here

What I expected to happen was...:
So I joined a multiplayer server. and I can do everything normal

What actually happened was...:
But, when I type my minecraft crashed it and happens for every multi player servers but I can do commands that involve / without crashing

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2.
3. ...