Note that I uninstalled all of the mods Im using excluding replay mod and the game still crashed. So this has to be a issue with replay mod.  This crashlog is with all mods I use.  Forge version https://prnt.sc/kjyt7d Other mods https://prnt.sc/kjytv9 Interesting thing is that I downloaded a minigame (Missile wars from 1.8) and the world loads just fine. the 1.12.2 worlds crash when I load them.  If I load a world that has nothing but void the game doesnt crash. The game still crashes even If the singleplayer recorder is checked or not. 
---- Minecraft Crash Report ----
WARNING: coremods are present:
  LoadingPlugin (replaymod-1.12.2-2.1.3.jar)
  BetterSprintingCore (Better-Sprinting-Mod-1.12.2.jar)
Contact their authors BEFORE contacting forge
// This doesn't make any sense!
Time: 8/17/18 4:47 PM
Description: Exception in server tick loop
java.lang.IllegalArgumentException: ChunkNibbleArrays should be 2048 bytes not: 0
	at net.minecraft.world.chunk.NibbleArray.(SourceFile:16)
	at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75823_a(AnvilChunkLoader.java:449)
	at net.minecraft.world.chunk.storage.AnvilChunkLoader.checkedReadChunkFromNBT__Async(AnvilChunkLoader.java:128)
	at net.minecraft.world.chunk.storage.AnvilChunkLoader.loadChunk__Async(AnvilChunkLoader.java:92)
	at net.minecraftforge.common.chunkio.ChunkIOProvider.run(ChunkIOProvider.java:70)
	at net.minecraftforge.common.chunkio.ChunkIOExecutor.syncChunkLoad(ChunkIOExecutor.java:92)
	at net.minecraft.world.gen.ChunkProviderServer.loadChunk(ChunkProviderServer.java:118)
	at net.minecraft.world.gen.ChunkProviderServer.func_186028_c(ChunkProviderServer.java:89)
	at net.minecraft.world.gen.ChunkProviderServer.func_186025_d(ChunkProviderServer.java:135)
	at net.minecraft.server.MinecraftServer.func_71222_d(MinecraftServer.java:344)
	at net.minecraft.server.integrated.IntegratedServer.func_71247_a(IntegratedServer.java:173)
	at net.minecraft.server.integrated.IntegratedServer.func_71197_b(IntegratedServer.java:196)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:486)
	at java.lang.Thread.run(Thread.java:745)
A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------
-- System Details --
Details:
	Minecraft Version: 1.12.2
	Operating System: Mac OS X (x86_64) version 10.11.6
	Java Version: 1.8.0_74, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 306725816 bytes (292 MB) / 872415232 bytes (832 MB) up to 3221225472 bytes (3072 MB)
	JVM Flags: 7 total; -Xmx3G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	FML: MCP 9.42 Powered by Forge 14.23.4.2750 Optifine OptiFine_1.12.2_HD_U_C6 15 mods loaded, 15 mods active
	States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
	| State   | ID                      | Version      | Source                                | Signature                                |
	|:------- |:----------------------- |:------------ |:------------------------------------- |:---------------------------------------- |
	| UCHIJAA | minecraft               | 1.12.2       | minecraft.jar                         | None                                     |
	| UCHIJAA | mcp                     | 9.42         | minecraft.jar                         | None                                     |
	| UCHIJAA | FML                     | 8.0.99.99    | forge-1.12.2-14.23.4.2750.jar         | e3c3d50c7c986df74c645c0ac54639741c90a557 |
	| UCHIJAA | forge                   | 14.23.4.2750 | forge-1.12.2-14.23.4.2750.jar         | e3c3d50c7c986df74c645c0ac54639741c90a557 |
	| UCHIJAA | replaymod-compat        | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | replaymod               | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | replaymod-editor        | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | replaymod-extras        | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | replaymod-online        | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | replaymod-recording     | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | replaymod-render        | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | replaymod-replay        | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | replaymod-simplepathing | 1.12.2-2.1.3 | replaymod-1.12.2-2.1.3.jar            | None                                     |
	| UCHIJAA | bettersprinting         | 2.1.0        | Better-Sprinting-Mod-1.12.2.jar       | None                                     |
	| UCHIJAA | worldedit               | 6.1.8        | worldedit-forge-mc1.12-6.1.8-dist.jar | None                                     |
	Loaded coremods (and transformers): 
LoadingPlugin (replaymod-1.12.2-2.1.3.jar)
  
BetterSprintingCore (Better-Sprinting-Mod-1.12.2.jar)
  chylex.bettersprinting.system.core.TransformerEntityPlayerSP
	GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.
	Profiler Position: N/A (disabled)
	Player Count: 0 / 8; []
	Type: Integrated Server (map_client.txt)
	Is Modded: Definitely; Client brand changed to 'fml,forge'
	OptiFine Version: OptiFine_1.12.2_HD_U_C6
	Render Distance Chunks: 12
	Mipmaps: 4
	Anisotropic Filtering: 1
	Antialiasing: 0
	Multitexture: false
	Shaders: null
	OpenGlVersion: 2.1 INTEL-10.14.73
	OpenGlRenderer: Intel(R) HD Graphics 6000
	OpenGlVendor: Intel Inc.
	CpuCount: 4