---- Minecraft Crash Report ---- WARNING: coremods are present:   FMLLoadingPlugin (MemoryFix-0.3.jar)   LabyModCoreMod (LabyMod-3.jar)   SkyblockAddonsLoadingPlugin (SkyblockAddons-1.5.2-for-MC-1.8.9.jar)   FMLLoadingPlugin (AutoGG-3.4 (1.8.9).jar)   FMLLoadingPlugin (MouseDelayFix-1.0.jar) Contact their authors BEFORE contacting forge // Who set us up the TNT? Time: 7/13/20 11:18 AM Description: Unexpected error java.lang.NullPointerException: Unexpected error     at AccumulationMethod.createAccumulation(AccumulationMethod.java:11)     at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1083)     at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:349)     at net.minecraft.client.main.Main.main(SourceFile:124)     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)     at java.lang.reflect.Method.invoke(Method.java:497)     at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)     at net.minecraft.launchwrapper.Launch.main(Launch.java:28) A detailed walkthrough of the error, its code path and all known details is as follows: --------------------------------------------------------------------------------------- -- System Details -- Details:     Minecraft Version: 1.8.9     Operating System: Windows 10 (amd64) version 10.0     Java Version: 1.8.0_51, Oracle Corporation     Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation     Memory: 591906624 bytes (564 MB) / 1040187392 bytes (992 MB) up to 2147483648 bytes (2048 MB)     JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M     IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0     FML: MCP 9.19 Powered by Forge 11.15.1.1855 23 mods loaded, 23 mods active     States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored     U    mcp{9.19} [Minecraft Coder Pack] (minecraft.jar)      U    FML{8.0.99.99} [Forge Mod Loader] (forge-1.8.9-11.15.1.1855.jar)      U    Forge{11.15.1.1855} [Minecraft Forge] (forge-1.8.9-11.15.1.1855.jar)      U    mousedelayfix{1.0} [MouseDelayFix] (minecraft.jar)      U    autotip{3.0.1} [Autotip] (Autotip-3.0.1 [1.8-1.12.2].jar)      U    modcore{0.1.35} [ModCore] (Sk1er Modcore-0.1.35 (1.8.9).jar)      U    ArmorStatusHUD{1.29} [ArmorStatusHUD] ([1.8.9] ArmorStatusHUD.jar)      U    examplemod{1.0} [examplemod] ([1.8.9] ArmorStatusHUD.jar)      U    bspkrsCore{7.01} [bspkrsCore] ([1.8.9] BspkrsCore.jar)      U    canelexkeystrokes{1.0} [Canelex Keystrokes] ([1.8.9] CanelexKeystrokes.jar)      U    perspectivemod{1.0} [Perspective Mod] ([1.8.9] Perspective Mod [fix2].jar)      U    pownscoordshud{1.0} [Powns' Coords HUD] ([1.8.9] Powns Coords HUD - 1.0.jar)      U    sidebarmod{2.0} [Sidebar Mod Revamp] ([1.8.9] Sidebar Mod Revamp.jar)      U    StatusEffectHUD{1.27} [StatusEffectHUD] ([1.8.9] StatusEffectHUD.jar)      U    wingsmod{1.2} [Wings Mod] ([1.8.9] Wings Mod-1.2.jar)      U    autogg{3.4} [AutoGG] (AutoGG-3.4 (1.8.9).jar)      U    fovcontrol{1.0} [FovControl] (fovcontrol-1.0.jar)      U    labymod{3.6.12} [LabyMod] (LabyMod-3.jar)      U    memoryfix{0.3} [MemoryFix] (MemoryFix-0.3.jar)      U    orangesimplemod{1.0} [orangesimplemod] (Orange's+Simple+Mods-1.2.jar)      U    quickplaypremium{1.0.4} [Quickplay Premium] (Quickplay Premium 1.8.9-1.0.4.jar)      U    skyblockaddons{1.5.2} [SkyBlock Addons] (SkyblockAddons-1.5.2-for-MC-1.8.9.jar)      U    enhancements{7.7} [Vanilla Enhancements] (Vanilla+Enhancements-7.7.jar)      Loaded coremods (and transformers):  FMLLoadingPlugin (MemoryFix-0.3.jar)   io.prplz.memoryfix.ClassTransformer LabyModCoreMod (LabyMod-3.jar)   net.labymod.core.asm.LabyModTransformer   net.labymod.addons.custommainmenu.asm.CustomMainMenuTransformer   net.labymod.addons.itemphysic.asm.ItemPhysicTransformer   net.labymod.addons.moreparticle.asm.MoreParticleTranformer   net.labymod.addons.motionblur.asm.MotionBlurTransformer SkyblockAddonsLoadingPlugin (SkyblockAddons-1.5.2-for-MC-1.8.9.jar)   codes.biscuit.skyblockaddons.tweaker.SkyblockAddonsTransformer FMLLoadingPlugin (AutoGG-3.4 (1.8.9).jar)   club.sk1er.mods.core.forge.ClassTransformer FMLLoadingPlugin (MouseDelayFix-1.0.jar)   io.prplz.mousedelayfix.ClassTransformer     GL info: ' Vendor: 'NVIDIA Corporation' Version: '4.6.0 NVIDIA 391.35' Renderer: 'GeForce GT 610/PCIe/SSE2'     Launched Version: 1.8.9-forge1.8.9-11.15.1.1855     LWJGL: 2.9.4     OpenGL: GeForce GT 610/PCIe/SSE2 GL version 4.6.0 NVIDIA 391.35, NVIDIA Corporation     GL Caps: Using GL 1.3 multitexturing. Using GL 1.3 texture combiners. Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported. Shaders are available because OpenGL 2.1 is supported. VBOs are available because OpenGL 1.5 is supported.     Using VBOs: No     Is Modded: Definitely; Client brand changed to 'fml,forge'     Type: Client (map_client.txt)     Resource Packs: FurfSky+ Release 1.7.1.zip     Current Language: English (US)     Profiler Position: N/A (disabled)     CPU: 4x Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz

try  replaceItemInInventory()  

How would i go about creating a new tool type? I'm specifically trying to make a tool that would function like a pickaxe but only for certain blocks. Thanks.

It means you're not actually overriding a method. i.e. the signature (name, parameters, return type) don't match a method in the parent class.

am I able to just add it? or do I have to use NBT? (I do not know how to do either..)