[ShopGUIPlus] Task #20 for ShopGUIPlus v1.15.0 generated an exception
java.lang.NullPointerException: null
at org.bukkit.craftbukkit.v1_12_R1.entity.CraftHumanEntity.openInventory(CraftHumanEntity.java:186) ~[spigot.jar:git-Spigot-4bd94dc-fb414fe]
at net.brcdev.shopgui.util.InventoryUtils$1.run(InventoryUtils.java:53) ~[?:?]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:71) ~[spigot.jar:git-Spigot-4bd94dc-fb414fe]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:353) [spigot.jar:git-Spigot-4bd94dc-fb414fe]
at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:739) [spigot.jar:git-Spigot-4bd94dc-fb414fe]
at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:406) [spigot.jar:git-Spigot-4bd94dc-fb414fe]
at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679) [spigot.jar:git-Spigot-4bd94dc-fb414fe]
at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577) [spigot.jar:git-Spigot-4bd94dc-fb414fe]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_161]
Can u help me please ?