Issue with Chest Shop

[NosferatwoRefine]

Sponge Version: 7.3.0
Forge Version: 2855
Total Economy Version: 1.8.1

When I tried to set up a shop with /shop buy it led to me getting an error message "Error occurred while executing command:null" I was pointing towards the chest while inputting the code, the same thing happened if I tried the /shop stock command, for the former I got the following in my console. I'm sure I have all of the correct permissions

[23:18:27] [Server thread/ERROR] [Sponge]: Error occurred while executing command 'shop buy' for source EntityPlayerMP['Nosferatwo11'/62, l='ThePoggersWorld', x=866.34, y=67.00, z=642.86]: null
java.lang.NullPointerException: null
at com.erigitic.commands.ShopCommand$Buy.execute(ShopCommand.java:238) ~[ShopCommand$Buy.class:?]
at org.spongepowered.api.command.args.ChildCommandElementExecutor.execute(ChildCommandElementExecutor.java:255) ~[ChildCommandElementExecutor.class:1.12.2-2838-7.3.0]
at org.spongepowered.api.command.spec.CommandSpec.process(CommandSpec.java:388) ~[CommandSpec.class:1.12.2-2838-7.3.0]
at org.spongepowered.common.command.SpongeCommandDispatcher.process(SpongeCommandDispatcher.java:355) ~[SpongeCommandDispatcher.class:1.12.2-2838-7.3.0]
at org.spongepowered.common.command.SpongeCommandManager.process(SpongeCommandManager.java:360) [SpongeCommandManager.class:1.12.2-2838-7.3.0]
at net.minecraft.command.ServerCommandManager.func_71556_a(SourceFile:665) [dh.class:?]
at net.minecraft.network.NetHandlerPlayServer.func_147361_d(NetHandlerPlayServer.java:962) [pa.class:?]
at net.minecraft.network.NetHandlerPlayServer.func_147354_a(NetHandlerPlayServer.java:941) [pa.class:?]
at net.minecraft.network.play.client.CPacketChatMessage.func_148833_a(SourceFile:37) [la.class:?]
at net.minecraft.network.play.client.CPacketChatMessage.func_148833_a(SourceFile:9) [la.class:?]
at org.spongepowered.common.event.tracking.phase.packet.PacketPhaseUtil.onProcessPacket(PacketPhaseUtil.java:219) [PacketPhaseUtil.class:1.12.2-2838-7.3.0]
at net.minecraft.network.PacketThreadUtil$1.redirect$zlc000$impl$redirectToPhaseTracker(SourceFile:540) [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_291]
at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_291]