[MC-210473] Burning certain blocks inside of an unlit nether portal crashes the game

The bug

If you burn a composter, a beehive, a bee nest, or a lectern inside of an unlit nether portal, the game will often crash. When you reopen the world after the crash, you will very briefly see two nether portal blocks in the bottom of the frame (and a fire block) and they will instantaneously shatter.

To reproduce

Build a nether portal frame.
Place a composter, a beehive, a bee nest, or a lectern inside the nether portal frame.
Use a flint and steel to light a fire on top of the flammable block.
Wait until the block burns away.
Often, the game crashes. However, sometimes the block will burn away without crashing and without lighting the nether portal.

Stack trace

1.16.4: crash-2021-01-04_02.23.39-server.txt

Description: Exception while ticking

java.lang.IllegalStateException: POI data mismatch: already registered at fx{x=77, y=4, z=-150}
	at azq.a(SourceFile:82)
	at azq.a(SourceFile:66)
	at azo.a(SourceFile:49)
	at aag.b(SourceFile:1260)
	at aob.execute(SourceFile:94)
	at aag.a(SourceFile:1259)
	at java.util.Optional.ifPresent(Optional.java:159)
	at aag.a(SourceFile:1259)
	at brx.a(SourceFile:269)
	at brx.a(SourceFile:217)
	at cxn.a(SourceFile:187)
	at java.lang.Iterable.forEach(Iterable.java:75)
	at cxn.b(SourceFile:186)
	at bue.b(SourceFile:140)
	at bws.b(SourceFile:303)
	at ceg$a.a(SourceFile:866)
	at cgh.a(SourceFile:293)
	at brx.a(SourceFile:231)
	at brx.a(SourceFile:217)
	at bws.a(SourceFile:251)
	at bws.a(SourceFile:185)
	at ceg$a.a(SourceFile:874)
	at aag.b(SourceFile:602)
	at bsl.b(SourceFile:84)
	at aag.a(SourceFile:357)
	at net.minecraft.server.MinecraftServer.b(SourceFile:871)
	at net.minecraft.server.MinecraftServer.a(SourceFile:811)
	at eng.a(SourceFile:91)
	at net.minecraft.server.MinecraftServer.w(SourceFile:670)
	at net.minecraft.server.MinecraftServer.a(SourceFile:257)
	at java.lang.Thread.run(Thread.java:745)

Paper's fix for this: https://github.com/PaperMC/Paper/commit/6b3a6aefae6654e9fe5e008b129cbad912e6d106

Credit

This was originally reported by Camilo Sepulveda as ~~MCL-16277~~, but that report was difficult to understand and it was created in the wrong project, so I created this new report.