Every time I try to open a world or play on a server the game crashes and displays this " The game crashed whilst mouseclicked event handler Error: java.lang.IllegalStateException: failed to create a child event loop"

What I expected to happen was...:
I was able to get on servers and worlds

What actually happened was...:
every time I tried to join a world or server an error popped up 

Steps to Reproduce:
1. Launch the new unified launcher 
2. click play
3. join a world or server