InteractBlockEvent Bug

[SjsolisZXA]

Hello, I've been using this plugin since API 5. I have many AdminShops on my server, but I figured I post the issue on here before I migrate onto another admin shop like plugin. Below is the log of when I tried to interact with the buy signs on my server.

SpongeForge Version: spongeforge-1.12.2-2705-7.1.0-BETA-3349
Sponge API Version: 7.1.0
AdminShop Version: AdminShop-1.10.2-1.8.2-universal
Economy Plugin: TotalEconomy-1.8.1

[10:39:41] [Server thread/ERROR] [Sponge]: Could not pass InteractBlockEvent$Secondary$MainHand$Impl to Plugin{id=adminshop, name=AdminShop, version=1.8.2, description=This plugin adds sign shops for users to buy items., source=.\mods\AdminShop-1.10.2-1.8.2-universal.jar}
java.lang.NoClassDefFoundError: org/spongepowered/api/event/cause/NamedCause
at io.github.hsyyid.adminshop.listeners.InteractBlockListener.onPlayerRightClickBlock(InteractBlockListener.java:164) ~[InteractBlockListener.class:?]
at org.spongepowered.common.event.listener.SecondaryListener_InteractBlockListener_onPlayerRightClickBlock79.handle(Unknown Source) ~[?:?]
at org.spongepowered.common.event.RegisteredListener.handle(RegisteredListener.java:95) ~[RegisteredListener.class:1.12.2-2705-7.1.0-BETA-3349]
at org.spongepowered.mod.event.SpongeModEventManager.post(SpongeModEventManager.java:383) [SpongeModEventManager.class:1.12.2-2705-7.1.0-BETA-3349]
at org.spongepowered.mod.event.SpongeModEventManager.extendedPost(SpongeModEventManager.java:443) [SpongeModEventManager.class:1.12.2-2705-7.1.0-BETA-3349]
at net.minecraft.server.management.PlayerInteractionManager.func_187251_a(PlayerInteractionManager.java:1189) [or.class:?]
at net.minecraft.network.NetHandlerPlayServer.redirect$onProcessRightClickBlock$zim000(NetHandlerPlayServer.java:2410) [pa.class:?]
at net.minecraft.network.NetHandlerPlayServer.func_184337_a(NetHandlerPlayServer.java:739) [pa.class:?]
at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.func_148833_a(SourceFile:55) [ma.class:?]
at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.func_148833_a(SourceFile:11) [ma.class:?]
at org.spongepowered.common.network.PacketUtil.onProcessPacket(PacketUtil.java:92) [PacketUtil.class:1.12.2-2705-7.1.0-BETA-3349]
at net.minecraft.network.PacketThreadUtil$1.redirect$onProcessPacket$zld000(SourceFile:539) [hv$1.class:?]
at net.minecraft.network.PacketThreadUtil$1.run(SourceFile:13) [hv$1.class:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_181]
at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_181]
at net.minecraft.util.Util.func_181617_a(SourceFile:46) [h.class:?]
at org.spongepowered.common.SpongeImplHooks.onUtilRunTask(SpongeImplHooks.java:293) [SpongeImplHooks.class:1.12.2-2705-7.1.0-BETA-3349]
at net.minecraft.server.MinecraftServer.redirect$onRun$zji000(MinecraftServer.java:3963) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:723) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:396) [nz.class:?]
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_181]
Caused by: java.lang.ClassNotFoundException: org.spongepowered.api.event.cause.NamedCause
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_181]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_181]
... 23 more
Caused by: java.lang.NullPointerException