Description: Ticking entity

java.lang.NullPointerException: Cannot invoke "net.minecraft.class_1799.method_7909()" because "armorItems" is null
at Not Enough Crashes deobfuscated stack trace.(1.16.5+build.4)
at net.minecraft.entity.LivingEntity.addCarmotParticle(LivingEntity:13329)
at net.minecraft.entity.LivingEntity.handler$djm015$tick(LivingEntity:13324)
at net.minecraft.entity.LivingEntity.tick(LivingEntity)
at net.minecraft.entity.mob.MobEntity.tick(MobEntity:342)
at net.minecraft.entity.passive.HorseBaseEntity.tick(HorseBaseEntity:592)
at net.minecraft.server.world.ServerWorld.tickEntity(ServerWorld:621)
at net.minecraft.class_3218$$Lambda$7902/0x00000000b4230618.accept(Unknown Source)
at net.minecraft.world.World.tickEntity(World:561)
at net.minecraft.server.world.ServerWorld.tick(ServerWorld:411)
at net.minecraft.server.MinecraftServer.tickWorlds(MinecraftServer:871)
at net.minecraft.server.MinecraftServer.tick(MinecraftServer:811)
at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer:91)
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer:670)
at net.minecraft.server.MinecraftServer.method_29739(MinecraftServer:257)
at net.minecraft.server.MinecraftServer$$Lambda$7376/0x000000003725df50.run(Unknown Source)
at java.lang.Thread.run(Thread.java:853)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Entity being ticked --
Details:
Entity Type: minecraft:horse (net.minecraft.class_1498)
Entity ID: 1900
Entity Name: Horse
Entity's Exact location: 1070.36, 70.00, -145.16
Entity's Block location: World: (1070,70,-146), Chunk: (at 14,4,14 in 66,-10; contains blocks 1056,0,-160 to 1071,255,-145), Region: (2,-1; contains chunks 64,-32 to 95,-1, blocks 1024,0,-512 to 1535,255,-1)
Entity's Momentum: 0.00, -0.08, 0.00
Entity's Passengers: []
Entity's Vehicle: ERROR NullPointerException: Cannot invoke "net.minecraft.class_1297.toString()" because the return value of "net.minecraft.class_1297.method_5854()" is null
Entity NBT: {DeathTime:0s,LeftHanded:0b,OnGround:1b,AbsorptionAmount:0.0f,Attributes:[{Name:"minecraft:generic.armor",Base:0.0d},{Name:"minecraft:generic.movement_speed",Base:0.19043790151531018d},{Name:"minecraft:generic.follow_range",Modifiers:[{Name:"Random spawn bonus",Operation:1,UUID:[I;1534536605,785205241,-2076911972,-760475603],Amount:-0.021576025492911717d}],Base:16.0d},{Name:"minecraft:generic.max_health",Base:23.0d},{Name:"minecraft:horse.jump_strength",Base:0.6269238008178512d}],Invulnerable:0b,Brain:{memories:{}},Age:0,Rotation:[331.3436f,0.0f],HurtByTimestamp:0,ArmorDropChances:[0.085f,0.085f,0.0f,0.085f],HandDropChances:[0.085f,0.085f],ForcedAge:0,cardinal_components:{"library_of_exile:entity_info":{spawn_pos:291370580774983L,dmg_stats:{enviroOrMobDmg:0.0f,map:[]},OTHER:"spawn"}},Hat:0b,ArmorItems:[{},{},{},{}],Temper:0,Air:300s,HandItems:[{},{}],CowboySpawned:0b,UUID:[I;-1021436673,-312131060,-1633756480,-402664186],BoundingBox:[1069.6642605166755d,70.0d,-145.85928755354246d,1071.0607448916755d,71.60000002384186d,-144.46280317854246d],Variant:1,Tame:0b,Bred:0b,FallDistance:0.0f,InLove:0,Motion:[0.0d,-0.0784000015258789d,0.0d],Fire:-1s,Health:23.0f,CanPickUpLoot:0b,HurtTime:0s,Pos:[1070.3625027041755d,70.0d,-145.16104536604246d],FallFlying:0b,PersistenceRequired:0b,EatingHaystack:0b,PortalCooldown:0}
Stacktrace:
at net.minecraft.class_1937.method_18472(class_1937.java:564)
at net.minecraft.class_3218.method_18765(class_3218.java:411)
at net.minecraft.server.MinecraftServer.method_3813(MinecraftServer.java:871)
at net.minecraft.server.MinecraftServer.method_3748(MinecraftServer.java:811)
at net.minecraft.class_1132.method_3748(class_1132.java:91)
at net.minecraft.server.MinecraftServer.method_29741(MinecraftServer.java:670)
at net.minecraft.server.MinecraftServer.method_29739(MinecraftServer.java:257)
at net.minecraft.server.MinecraftServer$$Lambda$7376/0x000000003725df50.run(Unknown Source)
at java.base/java.lang.Thread.run(Thread.java:853)
-- Affected level --
Details:
All players: 1 total; [class_3222['K0RR'/40, l='ServerWorld minecraft:overworld New World', x=628.20, y=64.00, z=249.61]]
Chunk stats: ServerChunkCache: 9110
Level dimension: minecraft:overworld
Level spawn location: World: (-256,68,-112), Chunk: (at 0,4,0 in -16,-7; contains blocks -256,0,-112 to -241,255,-97), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Level time: 193958 game time, 12533 day time
Level name: New World
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Level weather: Rain time: 164176 (now: false), thunder time: 2631 (now: true)
Known server brands: fabric
Level was modded: true
Level storage version: 0x04ABD - Anvil
-- System Details --
Details:
Minecraft Version: 1.16.5
Minecraft Version ID: 1.16.5
Operating System: Linux (amd64) version 5.8.0-44-generic
Java Version: 15.0.2, AdoptOpenJDK
Java VM Version: Eclipse OpenJ9 VM (JRE 15 Linux amd64-64-Bit Compressed References 20210121_172 (JIT enabled, AOT enabled)
OpenJ9 - 345e1b09e
OMR - 741e94ea8
JCL - 863b523566 based on jdk-15.0.2+7), Eclipse OpenJ9

Cannot reproduce on my end. Also, it doesn't seem to be caused by VisualOverhaul, since the log doesn't mention anything regarding VisualOverhaul. The log says it's caused by something to do with horses, and it also seems to be thundering in your world. Maybe something to do with skeleton horses?

Cannot reproduce too. Should have checked this second time before reporting.
When a block is on a jukebox the "fake block" texture is visible from (only?) two sides.

Probably an issue with Sodium, here I used a newer build.