(RESOLVED) Game is crashing: java.lang.IllegalArgumentException: bound must be positive

As the title states, I'm running into a very annoying issue. The game keeps crashing and this seems to be the main error that's shown up the past five times it's crashed:

---- Minecraft Crash Report ----
// Shall we play a game?

Time: 11/3/20 5:08 AM
Description: Exception ticking world

java.lang.IllegalArgumentException: bound must be positive
	at java.util.Random.nextInt(Random.java:388) ~[?:1.8.0_252] {}
	at net.minecraft.world.spawner.WorldEntitySpawner.spawnEntitiesInChunk(WorldEntitySpawner.java:95) ~[?:?] {re:classloading}
	at net.minecraft.world.server.ServerChunkProvider.lambda$tickChunks$5(ServerChunkProvider.java:372) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at it.unimi.dsi.fastutil.longs.Long2ObjectLinkedOpenHashMap$1.forEach(Long2ObjectLinkedOpenHashMap.java:1661) ~[fastutil-8.2.1.jar:?] {}
	at com.google.common.collect.Iterables$UnmodifiableIterable.forEach(Iterables.java:105) ~[guava-21.0.jar:?] {}
	at net.minecraft.world.server.ServerChunkProvider.tickChunks(ServerChunkProvider.java:355) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.world.server.ServerChunkProvider.tick(ServerChunkProvider.java:331) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.world.server.ServerWorld.tick(ServerWorld.java:316) ~[?:?] {re:classloading}
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:886) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:821) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:120) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:662) [?:?] {re:classloading,pl:accesstransformer:B}
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_252] {}


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

-- Head --
Thread: Server thread
Stacktrace:
	at java.util.Random.nextInt(Random.java:388)
	at net.minecraft.world.spawner.WorldEntitySpawner.spawnEntitiesInChunk(WorldEntitySpawner.java:95)
	at net.minecraft.world.server.ServerChunkProvider.lambda$tickChunks$5(ServerChunkProvider.java:372)
	at it.unimi.dsi.fastutil.longs.Long2ObjectLinkedOpenHashMap$1.forEach(Long2ObjectLinkedOpenHashMap.java:1661)
	at com.google.common.collect.Iterables$UnmodifiableIterable.forEach(Iterables.java:105)
	at net.minecraft.world.server.ServerChunkProvider.tickChunks(ServerChunkProvider.java:355)
	at net.minecraft.world.server.ServerChunkProvider.tick(ServerChunkProvider.java:331)
	at net.minecraft.world.server.ServerWorld.tick(ServerWorld.java:316)

-- Affected level --
Details:
	All players: 1 total; [ServerPlayerEntity['Dev'/155, l='Voidlands', x=-39.25, y=95.87, z=-56.17]]
	Chunk stats: ServerChunkCache: 1089
	Level dimension: DimensionType{gemstone_forge:ebony_lands}
	Derived: true
	Level name: Voidlands
	Level seed: 2600708484192271368
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: {}
	Level spawn location: World: (55,63,46), Chunk: (at 7,3,14 in 3,2; contains blocks 48,0,32 to 63,255,47), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 1284 game time, 1284 day time
	Known server brands: forge
	Level was modded: true
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 43996 (now: false), thunder time: 37183 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:886)
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:821)
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:120)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:662)
	at java.lang.Thread.run(Thread.java:748)

I really wish I understood what exactly was going on or why it was even crashing in the first place. At first I thought it was something to do with the new mob I added, but after disabling its spawning entirely, it's still crashing. All I'm trying to do is get one of my other mobs to actually spawn :\

I would also like to add that both of the mobs I've added to my workspace were made for 1.15.2 in Blockbench, the same version the mod was made for, so I'm honestly confused.