Good plugin, works well, but one thing:
I can't sell every Item, because the material name doesen't always fit in the Sign-Line.
Is there any command to create a Chest Shop? If not I recommend adding a command to create a Shop.
e.g. /chestshop create <price>, adding the holding Item to the Shop.
Else it's a very good Plugin, thanks!

This work well for me and really easy to install! I play in my scalacube server with my friends all work perfectly! Thank you, sir!

Doesn't work

org.bukkit.command.CommandException: Cannot execute command 'chestshop' in plugin ChestShop v1.0.5 - plugin is disabled.
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:37) ~[paper-mojangapi-1.21.1-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.command.brigadier.bukkit.BukkitCommandNode$BukkitBrigCommand.run(BukkitCommandNode.java:91) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at com.mojang.brigadier.context.ContextChain.runExecutable(ContextChain.java:73) ~[brigadier-1.3.10.jar:?]
at net.minecraft.commands.execution.tasks.ExecuteCommand.execute(ExecuteCommand.java:31) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.commands.execution.tasks.ExecuteCommand.execute(ExecuteCommand.java:19) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.commands.execution.UnboundEntryAction.lambda$bind$0(UnboundEntryAction.java:8) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.commands.execution.CommandQueueEntry.execute(CommandQueueEntry.java:5) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.commands.execution.ExecutionContext.runCommandQueue(ExecutionContext.java:103) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.commands.Commands.executeCommandInContext(Commands.java:443) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.commands.Commands.performCommand(Commands.java:350) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.commands.Commands.performCommand(Commands.java:337) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.commands.Commands.performCommand(Commands.java:332) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.network.ServerGamePacketListenerImpl.performUnsignedChatCommand(ServerGamePacketListenerImpl.java:2218) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.network.ServerGamePacketListenerImpl.lambda$handleChatCommand$11(ServerGamePacketListenerImpl.java:2192) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.TickTask.run(TickTask.java:18) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:151) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:24) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1537) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:201) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:125) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1514) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1507) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.util.thread.BlockableEventLoop.managedBlock(BlockableEventLoop.java:135) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.MinecraftServer.managedBlock(MinecraftServer.java:1466) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.MinecraftServer.waitUntilNextTick(MinecraftServer.java:1473) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1318) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:330) ~[paper-1.21.1.jar:1.21.1-81-13a2395]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]