Hello everyone,
since I updated to the last NBTAPI version (v2.12.0), I'll keep getting this error:

[Server thread/WARN]: [NBTAPI] Error during 'EmptyItemTest' test!
de.tr7zw.nbtapi.NbtApiException: [?][2.12.0]Item reported to have data
at de.tr7zw.nbtapi.plugin.tests.items.EmptyItemTest.test(EmptyItemTest.java:18) ~[item-nbt-api-plugin-2.12.0.jar:?]
at de.tr7zw.nbtapi.plugin.NBTAPI.onEnable(NBTAPI.java:220) ~[item-nbt-api-plugin-2.12.0.jar:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:281) ~[purpur-api-1.19.4-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.plugin.manager.PaperPluginInstanceManager.enablePlugin(PaperPluginInstanceManager.java:189) ~[purpur-1.19.4.jar:git-Purpur-1982]
at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.enablePlugin(PaperPluginManagerImpl.java:104) ~[purpur-1.19.4.jar:git-Purpur-1982]
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:507) ~[purpur-api-1.19.4-R0.1-SNAPSHOT.jar:?]
at org.bukkit.craftbukkit.v1_19_R3.CraftServer.enablePlugin(CraftServer.java:572) ~[purpur-1.19.4.jar:git-Purpur-1982]
at org.bukkit.craftbukkit.v1_19_R3.CraftServer.enablePlugins(CraftServer.java:483) ~[purpur-1.19.4.jar:git-Purpur-1982]
at net.minecraft.server.MinecraftServer.loadWorld0(MinecraftServer.java:643) ~[purpur-1.19.4.jar:git-Purpur-1982]
at net.minecraft.server.MinecraftServer.loadLevel(MinecraftServer.java:442) ~[purpur-1.19.4.jar:git-Purpur-1982]
at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:345) ~[purpur-1.19.4.jar:git-Purpur-1982]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1120) ~[purpur-1.19.4.jar:git-Purpur-1982]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:325) ~[purpur-1.19.4.jar:git-Purpur-1982]
at java.lang.Thread.run(Thread.java:833) ~[?:?]
[Server thread/INFO]: [NBTAPI] EmptyItemTest: [?][2.12.0]Item reported to have data
[Server thread/WARN]: [NBTAPI] WARNING! This version of NBT-API seems to be broken with your Spigot version! Plugins that don't check properly may throw Exeptions, crash or have unexpected behaviors!

I am using a Purpur Server, version 1.19.4 (Build 1982).

I don't know much about coding, still learning, but I experience a duplication glitch on my server and I think it's because of this. If you need some more information to solve this "issue", please ask.

Thanks :)

Okay, thank you for your worldrecord-fast reply.
Then I have to ask other developers for other plugins.

I'll fix it tonight, whatever broke there.

Ah crap right, someone also reported that for 1.19. Not sure what makes 1.19 different, will have to look into it.
But this test is more of a technicality, it shouldn't impact other plugins that use the API(usually).