[MC-168147] Java.Lang.NullPointerException

My Computer Minecraft is in 1.15 and all the single-player worlds work fine, but when i try to open Hypixel, it goes in then says saving world and my Minecraft crashes. PLS I NEED HELP

Stack trace

1.15: crash-2019-12-16_20.23.01-client.txt

Description: Unexpected error

java.lang.NullPointerException: Unexpected error
	at dbl.O(SourceFile:2104)
	at edr.a(SourceFile:24)
	at dbl.n(SourceFile:1433)
	at dbl.d(SourceFile:922)
	at dbl.b(SourceFile:585)
	at net.minecraft.client.main.Main.main(SourceFile:202)