Minecraft crashes when loading resource pack due to "tessellating block model"

Minecraft crashes while "tessellating block model. Only happens when loading my resource pack. Crash report: 

---- Minecraft Crash Report ----
// Daisy, daisy...
Time: 16/12/20 4:13 PM
Description: Tesselating block model

java.lang.ArrayIndexOutOfBoundsException: 61387
at brr.a(SourceFile:14)
at bsv.w(SourceFile:411)
at java.util.Optional.orElseGet(Optional.java:267)
at bsv.g(SourceFile:405)
at dzr.b(SourceFile:10)
at dwt.b(SourceFile:788)
at dwt.c(SourceFile:770)
at dkp.a(SourceFile:43)
at dwt.a(SourceFile:770)
at ecv.a(SourceFile:137)
at dzr.a(SourceFile:14)
at dzr.b(SourceFile:22)
at dko.h(SourceFile:58)
at dko.a(SourceFile:112)
at eaz.a(SourceFile:141)
at eaz.a(SourceFile:127)
at eaz.b(SourceFile:76)
at eaz.a(SourceFile:47)
at eax.a(SourceFile:61)
at ecu$c$b.a(SourceFile:512)
at ecu$c$b.a(SourceFile:434)
at ecu.a(SourceFile:136)
at java.util.concurrent.CompletableFuture.uniCompose(CompletableFuture.java:952)
at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:926)
at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474)
at java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1632)
at java.util.concurrent.CompletableFuture$AsyncRun.exec(CompletableFuture.java:1618)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------
-- Head --
Thread: Render thread
Stacktrace:
at brr.a(SourceFile:14)
at bsv.w(SourceFile:411)
at java.util.Optional.orElseGet(Optional.java:267)
at bsv.g(SourceFile:405)
at dzr.b(SourceFile:10)
at dwt.b(SourceFile:788)
at dwt.c(SourceFile:770)
at dkp.a(SourceFile:43)
at dwt.a(SourceFile:770)
at ecv.a(SourceFile:137)
at dzr.a(SourceFile:14)
at dzr.b(SourceFile:22)
at dko.h(SourceFile:58)
at dko.a(SourceFile:112)
at eaz.a(SourceFile:141)
at eaz.a(SourceFile:127)
at eaz.b(SourceFile:76)

-- Block model being tesselated --
Details:
Block: Block{minecraft:oak_leaves}[distance=4,persistent=false]
Block location: World: (479,75,-135), Chunk: (at 15,4,9 in 29,-9; contains blocks 464,0,-144 to 479,255,-129), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
Using AO: true
Stacktrace: at eaz.a(SourceFile:47)

-- Block being tesselated --
Details:
Block: Block{minecraft:oak_leaves}[distance=4,persistent=false]
Block location: World: (479,75,-135), Chunk: (at 15,4,9 in 29,-9; contains blocks 464,0,-144 to 479,255,-129), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
Stacktrace: at eax.a(SourceFile:61)

-- Affected level --
Details:
All players: 1 total; [dzm['F_Rex'/14, l='ClientLevel', x=450.97, y=83.69, z=-103.04]]
Chunk stats: Client Chunk Cache: 2601, 716
Level dimension: minecraft:overworld
Level spawn location: World: (192,71,160), Chunk: (at 0,4,0 in 12,10; contains blocks 192,0,160 to 207,255,175), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 41825 game time, 41825 day time
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at dwt.a(SourceFile:449)
at djz.c(SourceFile:2239)
at ecu.a(SourceFile:140)
at java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:760)
at java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:736)
at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474)
at java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1632)
at java.util.concurrent.CompletableFuture$AsyncRun.exec(CompletableFuture.java:1618)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

-- System Details --
Details: Minecraft Version: 1.16.4
Minecraft Version ID: 1.16.4
Operating System: Mac OS X (x86_64) version 10.15.6
Java Version: 1.8.0_74, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1450258912 bytes (1383 MB) / 2147483648 bytes (2048 MB) up to 2147483648 bytes (2048 MB)
CPUs: 4
JVM Flags: 8 total; -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
Launched Version: 1.16.4
Backend library: LWJGL version 3.2.1 build 12
Backend API: ~~ERROR~~ IllegalStateException: Rendersystem called from wrong thread
GL Caps: Using framebuffer using ARB_framebuffer_object extension
Using VBOs: Yes
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
GPU Warnings: version: 2.1
Graphics mode: fancy
Resource Packs: vanilla, file/F_rex's Switch Pack
Current Language: English (US)
CPU: 4x Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz