https://pastebin.com/nPtkCWfK

Steps to reproduce
Add to server
Add to Client
Join Server
Press "Escape" key to go to main menu
Press "Back to Game" Button, Client crashes

(Client does not crash if you use the "Escape" button to return to world)

This is certainly strange. The way I handle long reach attacks in 1.15.2 may be the issue here, as I am looking for left click input to determine if an extended reach attack was successful. I never accounted for a situation like this, where the game is paused and the player is resuming their game. This crash specifically happens because the client is trying to access the attribute value for attack reach i made, but it is somehow becoming null in this situation.

Try out the latest version for 1.15.2. I have added a null check for the attribute, hopefully that should resolve this issue.