The intro is well done in that it made me expect a horror concept and reminded me a bit of evangelion. Then, the game tried to start, and I encountered that same Godot error:
"ERROR: Resumed function '_process()' after yield, but class instance is gone. At script: res://entities/spawn_portal/spawn_portal.gd:43
At: modules/gdscript/gdscript_function.cpp:1873"
Got an entity that's initiating a condition and then destroying itself before the condition can resolve?