Plugin error.java

>.... [17:39:09 ERROR]: Could not pass event InventoryClickEvent to UltimateShops v2.0.6
java.lang.NullPointerException: null
at thirtyvirus.ultimateshops.events.inventory.InventoryClickHandler.customerGUI(InventoryClickHandler.java:592) ~[?:?]
at thirtyvirus.ultimateshops.events.inventory.InventoryClickHandler.onInventoryClick(InventoryClickHandler.java:112) ~[?:?]
at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor28.execute(Unknown Source) ~[?:?]
at org.bukkit.plugin.EventExecutor.lambda$create$1(EventExecutor.java:69) ~[patched_1.16.1.jar:git-Paper-20]
at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:80) ~[patched_1.16.1.jar:git-Paper-20]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[patched_1.16.1.jar:git-Paper-20]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:607) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.PlayerConnection.a(PlayerConnection.java:2421) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.PacketPlayInWindowClick.a(SourceFile:32) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.PacketPlayInWindowClick.a(SourceFile:10) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.PlayerConnectionUtils.lambda$ensureMainThread$0(PlayerConnectionUtils.java:23) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.TickTask.run(SourceFile:18) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.IAsyncTaskHandler.executeTask(IAsyncTaskHandler.java:136) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.IAsyncTaskHandler.executeNext(IAsyncTaskHandler.java:109) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.MinecraftServer.aZ(MinecraftServer.java:1136) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.MinecraftServer.executeNext(MinecraftServer.java:1129) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:119) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.MinecraftServer.sleepForTick(MinecraftServer.java:1090) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.MinecraftServer.v(MinecraftServer.java:1004) ~[patched_1.16.1.jar:git-Paper-20]
at net.minecraft.server.v1_16_R1.MinecraftServer.lambda$a$0(MinecraftServer.java:177) ~[patched_1.16.1.jar:git-Paper-20]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_212]