Game crashes upon launch after pressing "Play"

Put the summary of the bug you're having here

What I expected to happen was...:
I run the launcher, press play, and the game starts like normal.

What actually happened was...:
The launcher runs normally, but when "Play" is pressed, the normal text runs, the game window opens for a second then closes. The crash report shows up. "java.lang.IllegalStateException: Cannot determine close requested state of uncreated window"

Steps to Reproduce:
1. Run the launcher
2. Press "Play"
3. ???
4. Profit (Actually it just crashes)