Stackmob giving a bunch of errors

[cool2000herobrine]

Describe the bug
It's spamming the console and not stacking mobs correctly. There could be 10 pigs in a 10x10x10 and instead of making 1 stack with 10 pigs it makes 3 stacks with 3,3,4.
To Reproduce
No idea, just have different types of animals in a 10x10x10 and I think it should work.

Expected behavior
It should have made 1 stack with 10 pigs.

Screenshots/Videos
None, got the crashlog though.

Bukkit/Spigot AND StackMob version:
Paper-133 stackmob 5.0.2

Additional context
Here is the server LOG

WARN [StackMob] Task #95 for StackMob v5.0.2 generated an exception
17.03 21:11:40 [Server] INFO java.lang.IllegalArgumentException: Stack size cannot be more than the configured stack size!
17.03 21:11:40 [Server] INFO at uk.antiperson.stackmob.entity.StackEntity.setSize(StackEntity.java:35) ~[?:?]
17.03 21:11:40 [Server] INFO at uk.antiperson.stackmob.entity.StackEntity.setSize(StackEntity.java:23) ~[?:?]
17.03 21:11:40 [Server] INFO at uk.antiperson.stackmob.entity.StackEntity.merge(StackEntity.java:179) ~[?:?]
17.03 21:11:40 [Server] INFO at uk.antiperson.stackmob.tasks.MergeTask.run(MergeTask.java:49) ~[?:?]
17.03 21:11:40 [Server] INFO at org.bukkit.craftbukkit.v1_15_R1.scheduler.CraftTask.run(CraftTask.java:84) ~[patched_1.15.2.jar:git-Paper-133]
17.03 21:11:40 [Server] INFO at org.bukkit.craftbukkit.v1_15_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:452) ~[patched_1.15.2.jar:git-Paper-133]
17.03 21:11:40 [Server] INFO at net.minecraft.server.v1_15_R1.MinecraftServer.b(MinecraftServer.java:1185) ~[patched_1.15.2.jar:git-Paper-133]
17.03 21:11:40 [Server] INFO at net.minecraft.server.v1_15_R1.DedicatedServer.b(DedicatedServer.java:430) ~[patched_1.15.2.jar:git-Paper-133]
17.03 21:11:40 [Server] INFO at net.minecraft.server.v1_15_R1.MinecraftServer.a(MinecraftServer.java:1112) ~[patched_1.15.2.jar:git-Paper-133]
17.03 21:11:40 [Server] INFO at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:934) ~[patched_1.15.2.jar:git-Paper-133]
17.03 21:11:40 [Server] INFO at java.lang.Thread.run(Thread.java:748) [?:1.8.0_191]