When I load up minecraft 1.16.3 and press singleplayer it does not load properly. This started happening after my PC unexpectedly shut down while I was playing my single player world and I did not properly save. So therefore every time I try and play singleplayer it just freezes then gives the dirt screen with "saving world" and then immediately crashes after a few seconds. It gives me this error message:

The game crashed whilst mouseclicked event handler
Error: java.lang.OutOfMemoryError: Java heap space
Exit Code: -1