What steps will reproduce the problem?

Simply install SilkSpawners #503, hook into SilkUtil and set the spawner using the entity ID. When you place the spawner, it successfully says "Placed {mob} Spawner". For a split second you'll see the correct mob inside the spawner, then all of the sudden it changes to a pig. When you break the spawner, out comes a stack trace.

Expected output

The spawner should place the correct mob once, and break without errors.

What do you see instead?

Errors & the details I already mentioned above.

Log file of the issue/error

[14:41:15] [Server thread/ERROR]: Could not pass event BlockBreakEvent to SilkSpawners v6.0.0-SNAPSHOT-b503 org.bukkit.event.EventException at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[minecraft.jar:git-PaperSpigot-"4c7641d"] at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:78) ~[minecraft.jar:git-PaperSpigot-"4c7641d"] at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[minecraft.jar:git-PaperSpigot-"4c7641d"] at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:517) [minecraft.jar:git-PaperSpigot-"4c7641d"] at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:502) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.PlayerInteractManager.breakBlock(PlayerInteractManager.java:286) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.PlayerInteractManager.a(PlayerInteractManager.java:215) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:640) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.PacketPlayInBlockDig.a(SourceFile:40) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.PacketPlayInBlockDig.a(SourceFile:10) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [minecraft.jar:git-PaperSpigot-"4c7641d"] at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_202] at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_202] at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:774) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:378) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:713) [minecraft.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:616) [minecraft.jar:git-PaperSpigot-"4c7641d"] at java.lang.Thread.run(Unknown Source) [?:1.8.0_202] Caused by: java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap.get(Unknown Source) ~[?:1.8.0_202] at de.dustplanet.util.SilkUtil.getCreatureName(SilkUtil.java:562) ~[?:?] at de.dustplanet.silkspawners.listeners.SilkSpawnersBlockListener.onBlockBreak(SilkSpawnersBlockListener.java:76) ~[?:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_202] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_202] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_202] at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_202] at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:300) ~[minecraft.jar:git-PaperSpigot-"4c7641d"] ... 18 more

/version output?

CraftBukkit version git-PaperSpigot-"4c7641d" (MC: 1.8.8) Implementing API version 1.8.8-R0.1-SNAPSHOT

SilkSpawners version

Development Build #503

Please provide any additional information below.

https://youtu.be/DQ5eI2thgeA

• Slow the video down to half speed to clearly see the initial mob being correctly selected, then changing to a pig.

At this point, the plugin is basically useless when used with GUIShop or any other plugin using SilkUtil.

Configurations are default and untouched.

Checklist

• I am aware that issues caused by /reload are ignored
• If there is a (potential) plugin conflict, I've identified the conflicting plugin
• I have added a valid /version output
• I have added a valid SilkSpawners version
• I have attached necessary information like a screenshot, my list of plugins, config or permissions file(s)

See, thing is, I would stick to that build, if the API wasn't completely different for setting an item stack mob type. I really shouldn't need to be adding support per each version of silk when you have compatibility fixes per each minecraft version the latest version of silk for 1.13 and below.

Sorry, I've misread your issue that you are using the API :)
Your reported issue is basically #152 - same stack trace

Ah yes, Hopefully my recording and stack can provide you some assistance. Later this week ill look into forking and fixing myself if you're short on time. A PR will come with that. I have a ton of people complaining GUIShop spawners aren't working when in-turn its silk :c

It's a development build, that means: bugs, instability and not working builds.
You are using MC 1.8.8, please stick to SilkSpawners v5.0.2 from BukkitDev