[MC-176637] Closing game during Mojang load screen causes NullPointerException

The bug

When closing the game while the Mojang load screen is shown, a NullPointerException occurs.

20w13b log

00:41:43.869 Reloading ResourceManager: Default
00:41:45.666 Stopping!
00:41:45.704 Shutdown failure!
java.lang.NullPointerException
	at ejn.close(SourceFile:100)
	at dij.close(SourceFile:925)
	at dij.k(SourceFile:913)
	at net.minecraft.client.main.Main.main(SourceFile:218)
00:41:46.090
00:41:46.090 Process ended with exit code 0

How to reproduce

Start the game
While the Mojang load screen is shown, press the X of the game window
Look at the log