When I created a shop, I cannot access the interface. I tried everything, even opened a server from scratch. This plugin was working recently, but it is not working anymore.

[EymenAkcan]

[17:30:52 ERROR]: Could not pass event PlayerInteractEvent to ClickShop v1.0.2
java.lang.NullPointerException: Cannot invoke "String.substring(int, int)" because "string" is null
at ClickShop-1.0.2.jar/me.clickism.clickshop.menu.Button.rainbow(Button.java:69) ~[ClickShop-1.0.2.jar:?]
at ClickShop-1.0.2.jar/me.clickism.clickshop.menu.edit.CustomizeButton.(CustomizeButton.java:20) ~[ClickShop-1.0.2.jar:?]
at ClickShop-1.0.2.jar/me.clickism.clickshop.menu.edit.EditShopMenu.setupButtons(EditShopMenu.java:24) ~[ClickShop-1.0.2.jar:?]
at ClickShop-1.0.2.jar/me.clickism.clickshop.menu.Menu.decorate(Menu.java:72) ~[ClickShop-1.0.2.jar:?]
at ClickShop-1.0.2.jar/me.clickism.clickshop.menu.Menu.open(Menu.java:55) ~[ClickShop-1.0.2.jar:?]
at ClickShop-1.0.2.jar/me.clickism.clickshop.events.ShopInteractEvent.onInteract(ShopInteractEvent.java:30) ~[ClickShop-1.0.2.jar:?]
at ClickShop-1.0.2.jar/me.clickism.clickshop.events.InteractEvent.handleInteract(InteractEvent.java:36) ~[ClickShop-1.0.2.jar:?]
at ClickShop-1.0.2.jar/me.clickism.clickshop.events.ShopInteractEvent.onPlayerInteract(ShopInteractEvent.java:20) ~[ClickShop-1.0.2.jar:?]
at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:80) ~[purpur-api-1.21.7-R0.1-SNAPSHOT.jar:?]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:71) ~[purpur-api-1.21.7-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.plugin.manager.PaperEventManager.callEvent(PaperEventManager.java:54) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.callEvent(PaperPluginManagerImpl.java:131) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:628) ~[purpur-api-1.21.7-R0.1-SNAPSHOT.jar:?]
at org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:526) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.level.ServerPlayerGameMode.useItemOn(ServerPlayerGameMode.java:480) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.network.ServerGamePacketListenerImpl.handleUseItemOn(ServerGamePacketListenerImpl.java:2128) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.network.protocol.game.ServerboundUseItemOnPacket.handle(ServerboundUseItemOnPacket.java:45) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.network.protocol.game.ServerboundUseItemOnPacket.handle(ServerboundUseItemOnPacket.java:10) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$0(PacketUtils.java:29) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.TickTask.run(TickTask.java:18) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:155) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:24) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1485) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:176) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:129) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1465) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1459) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.util.thread.BlockableEventLoop.runAllTasks(BlockableEventLoop.java:118) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.MinecraftServer.waitUntilNextTick(MinecraftServer.java:1420) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1301) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:313) ~[purpur-1.21.7.jar:1.21.7-2477-60bdf1c]
at java.base/java.lang.Thread.run(Thread.java:1447) ~[?:?]