[Server thread/FATAL] [minecraft/MinecraftServer]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NoClassDefFoundError: net/minecraft/client/gui/GuiScreen
        at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_221]
        at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_221]
        at net.minecraft.util.Util.runTask(SourceFile:531) [h.class:?]
        at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:723) [MinecraftServer.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.updateTimeLightAndEntities(DedicatedServer.java:397) [nz.class:?]
        at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:668) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_221]
Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/gui/GuiScreen
        at com.ferreusveritas.dynamictrees.items.Staff.onItemUse(Staff.java:126) ~[Staff.class:?]
        at net.minecraftforge.common.ForgeHooks.onPlaceItemIntoWorld(ForgeHooks.java:889) ~[ForgeHooks.class:?]
        at net.minecraft.item.ItemStack.onItemUse(ItemStack.java:186) ~[aip.class:?]
        at net.minecraft.server.management.PlayerInteractionManager.processRightClickBlock(PlayerInteractionManager.java:492) ~[or.class:?]
        at net.minecraft.network.NetHandlerPlayServer.processTryUseItemOnBlock(NetHandlerPlayServer.java:741) ~[pa.class:?]
        at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.processPacket(SourceFile:55) ~[ma.class:?]
        at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.processPacket(SourceFile:11) ~[ma.class:?]
        at net.minecraft.network.PacketThreadUtil$1.run(SourceFile:13) ~[hv$1.class:?]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_221]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_221]
        at net.minecraft.util.Util.runTask(SourceFile:529) ~[h.class:?]
        ... 5 more