I attempted to enter a nether portal in survival mode and the purple visual swirled for a few seconds then froze, then the window closed and the launcher opened. I attempted to do the same again and it crashed again, although this time it supplied a crash report:

---- Minecraft Crash Report -------- Minecraft Crash Report ----// Daisy, daisy...
Time: 6/5/20 12:03 AMDescription: Ticking player
java.lang.NullPointerException: Ticking player at ze.a(SourceFile:651) at aoj.bg(SourceFile:1900) at aoj.ad(SourceFile:437) at aov.ad(SourceFile:320) at aoj.j(SourceFile:419) at aov.j(SourceFile:2181) at bdy.j(SourceFile:275) at ze.w_(SourceFile:418) at zv.b(SourceFile:206) at me.a(SourceFile:234) at zu.c(SourceFile:171) at net.minecraft.server.MinecraftServer.b(SourceFile:885) at net.minecraft.server.MinecraftServer.a(SourceFile:812) at eov.a(SourceFile:93) at net.minecraft.server.MinecraftServer.v(SourceFile:671) at net.minecraft.server.MinecraftServer.a(SourceFile:256) at net.minecraft.server.MinecraftServer$$Lambda$3885/1076037183.run(Unknown Source) at java.lang.Thread.run(Thread.java:745)

A detailed walkthrough of the error, its code path and all known details is as follows:---------------------------------------------------------------------------------------
– Head --Thread: Server threadStacktrace: at ze.a(SourceFile:651) at aoj.bg(SourceFile:1900) at aoj.ad(SourceFile:437) at aov.ad(SourceFile:320) at aoj.j(SourceFile:419) at aov.j(SourceFile:2181) at bdy.j(SourceFile:275)
– Player being ticked --Details: Entity Type: minecraft:player (ze) Entity ID: 268 Entity Name: bugbears Entity's Exact location: -11.13, 11.00, -206.84 Entity's Block location: World: (-12,11,-207), Chunk: (at 4,0,1 in -1,-13; contains blocks -16,0,-208 to -1,255,-193), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1) Entity's Momentum: 0.00, -0.08, 0.00 Entity's Passengers: [] Entity's Vehicle: ~_ERROR~ NullPointerException: nullStacktrace: at ze.w_(SourceFile:418) at zv.b(SourceFile:206) at me.a(SourceFile:234)
– Ticking connection --Details: Connection: me@66f82cb4Stacktrace: at zu.c(SourceFile:171) at net.minecraft.server.MinecraftServer.b(SourceFile:885) at net.minecraft.server.MinecraftServer.a(SourceFile:812) at eov.a(SourceFile:93) at net.minecraft.server.MinecraftServer.v(SourceFile:671) at net.minecraft.server.MinecraftServer.a(SourceFile:256) at net.minecraft.server.MinecraftServer$$Lambda$3885/1076037183.run(Unknown Source) at java.lang.Thread.run(Thread.java:745)
– System Details --Details: Minecraft Version: 1.16 Pre-release 1 Minecraft Version ID: 1.16-pre1 Operating System: Windows 10 (amd64) version 10.0 Java Version: 1.8.0_51, Oracle Corporation Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation Memory: 1225991304 bytes (1169 MB) / 2113929216 bytes (2016 MB) up to 2147483648 bytes (2048 MB) CPUs: 12 JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M Player Count: 1 / 8; [ze['bugbears'/268, l='ServerLevel[1.16 pre survival]', x=-11.13, y=11.00, z=-206.84]] Data Packs: vanilla Type: Integrated Server (map_client.txt) Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.