[2021] Game crashes when I turn asset editor on

Originally posted by Pectus Solentis: The error window says "VirtualAlloc remapping failed".

This is definitely the game running out of memory. You can increase the size of your pagefile to allow more flexibility.

If you use mods, then I would also recommend disabling any you don't absolutely need while working in the editor. Most of them are designed for the simulation and don't work correctly in the editor, so a mod acting up in the editor might cause errors (even if you don't see them pop up), which uses additional memory causing the crash.