There is a very critical bug, where if a spawner is placed on a server it will create MASSIVE log files on the other players computer (15GB+) How to reproduce: Start a minecraft server, log in, type this command: 

/give @p spawner{BlockEntityTag:{SpawnData:

,SpawnPotentials:\\{Weight:1,Entity:{id:"minecraft:iron_golem"}}}} 1

Place the spawner, go to your %appdata& > .minecraft > logs and you will get extremely large error logs with this error being spammed so bad that it can rack up in the gigabytes in minutes: 

[20:27:28] [Render thread/WARN]: Exception loading entity: [20:27:28] [Render thread/WARN]: Exception loading entity: u: Loading entity NBT at apx.f(SourceFile:1663) ~[1.16.2.jar:?] at aqb.a(SourceFile:473) ~[1.16.2.jar:?] at aqb$$Lambda$3815/258352473.accept(Unknown Source) ~[?:?] at x.a(SourceFile:402) ~[1.16.2.jar:?] at aqb.a(SourceFile:472) ~[1.16.2.jar:?] at aqb.b(SourceFile:535) [1.16.2.jar:?] at aqb.a(SourceFile:516) [1.16.2.jar:?] at bqw.d(SourceFile:254) [1.16.2.jar:?] at ech.a(SourceFile:22) [1.16.2.jar:?] at ech.a(SourceFile:12) [1.16.2.jar:?] at ebv.a(SourceFile:107) [1.16.2.jar:?] at ebv.b(SourceFile:96) [1.16.2.jar:?] at ebv$$Lambda$3717/1236061074.run(Unknown Source) [1.16.2.jar:?] at ebv.a(SourceFile:128) [1.16.2.jar:?] at ebv.a(SourceFile:96) [1.16.2.jar:?] at dzw.a(SourceFile:1260) [1.16.2.jar:?] at dzr.a(SourceFile:727) [1.16.2.jar:?] at dzr.a(SourceFile:546) [1.16.2.jar:?] at djw.e(SourceFile:1023) [1.16.2.jar:?] at djw.e(SourceFile:656) [1.16.2.jar:?] at net.minecraft.client.main.Main.main(SourceFile:215) [1.16.2.jar:?]Caused by: java.lang.ClassCastException: dwl cannot be cast to aag at baf.a(SourceFile:170) ~[1.16.2.jar:?] at apx.f(SourceFile:1654) ~[1.16.2.jar:?] ... 20 more