The game crashed whilst rendering overlay
Error: n: Non [a-z0-9/._-] character in path of location: minecraft:random stuff/fire
This is what the game is telling me when I try to launch the game.
Related issues
duplicates
Comments

Should be fixed in the newest pre-release which curremtly is 1.15-pre3
Remove your texture pack and you may ask the creator to update it. See MC-135110