[1.7.10] NullPointerException during harvest event

[flamedragonX2]

So I created a pickaxe that when mining stone drops my custom block, and has a 25% chance to set the player on fire when mining a block. Code for harvest event below:

 

(Note: some of it is obfuscated with xxxx to keep names a secret)

 

@SubscribeEvent
public void xxxxPick(HarvestDropsEvent event)
{
	ItemStack theTool = event.harvester.getCurrentEquippedItem(); //[b]THIS[/b] is line 38, which was mentioned in the crash report
	if(theTool != null)
	{
		if(theTool.getItem() == ToolManager.xxxxPickaxe)
		{	
			if(random.nextInt(4) == 0)
			{
				event.harvester.setFire(5);
			}

			if(event.block != null)
			{
				if(event.block == Blocks.stone)
				{
					event.drops.clear();
					event.drops.add(new ItemStack(Item.getItemFromBlock(myBlocksClass.myCustomStone)));
				}
			}				
		}
	}

 

However, occasionally I get a crash report, stating a NullPointerException has occured doing my custom pick event. This really confuses me since I checked to see if both the block and the ItemStack for the tool are not null before using them. Example below:

 

 

// Hi. I'm Minecraft, and I'm a crashaholic.

 

Time: 3/21/16 7:12 PM

Description: Exception ticking world

 

java.lang.NullPointerException: Exception ticking world

at net.xxxxxx.events.HarvestingEvents.xxxxPick(HarvestingEvents.java:38)

at cpw.mods.fml.common.eventhandler.ASMEventHandler_6_HarvestingEvents_xxxxPick_HarvestDropsEvent.invoke(.dynamic)

at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54)

at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:140)

at net.minecraftforge.event.ForgeEventFactory.fireBlockHarvesting(ForgeEventFactory.java:162)

at net.minecraft.block.Block.dropBlockAsItemWithChance(Block.java:806)

at net.minecraft.block.Block.dropBlockAsItem(Block.java:795)

at net.minecraft.block.BlockBush.checkAndDropBlock(BlockBush.java:74)

at net.minecraft.block.BlockBush.updateTick(BlockBush.java:64)

at net.minecraft.world.WorldServer.func_147456_g(WorldServer.java:408)

at net.minecraft.world.WorldServer.tick(WorldServer.java:191)

at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:692)

at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614)

at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:118)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485)

at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752)

 

 

A detailed walkthrough of the error, its code path and all known details is as follows:

---------------------------------------------------------------------------------------

 

-- Head --

Stacktrace:

at net.xxxxxxx.events.HarvestingEvents.xxxxPick(HarvestingEvents.java:38)

at cpw.mods.fml.common.eventhandler.ASMEventHandler_6_HarvestingEvents_xxxxPick_HarvestDropsEvent.invoke(.dynamic)

at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54)

at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:140)

at net.minecraftforge.event.ForgeEventFactory.fireBlockHarvesting(ForgeEventFactory.java:162)

at net.minecraft.block.Block.dropBlockAsItemWithChance(Block.java:806)

at net.minecraft.block.Block.dropBlockAsItem(Block.java:795)

at net.minecraft.block.BlockBush.checkAndDropBlock(BlockBush.java:74)

at net.minecraft.block.BlockBush.updateTick(BlockBush.java:64)

at net.minecraft.world.WorldServer.func_147456_g(WorldServer.java:408)

at net.minecraft.world.WorldServer.tick(WorldServer.java:191)

 

-- Affected level --

Details:

Level name: New Worldwq346g344v632v2453v

All players: 1 total; [EntityPlayerMP['Player189'/19119, l='New Worldwq346g344v632v2453v', x=-73.43, y=72.00, z=185.88]]

Chunk stats: ServerChunkCache: 647 Drop: 0

Level seed: -2949494732709534244

Level generator: ID 00 - default, ver 1. Features enabled: true

Level generator options:

Level spawn location: World: (-69,64,258), Chunk: (at 11,4,2 in -5,16; contains blocks -80,0,256 to -65,255,271), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)

Level time: 25685 game time, 25685 day time

Level dimension: 0

Level storage version: 0x04ABD - Anvil

Level weather: Rain time: 117553 (now: false), thunder time: 9149 (now: false)

Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true

Stacktrace:

at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:692)

at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614)

at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:118)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485)

at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752)

 

-- System Details --

Details:

Minecraft Version: 1.7.10

Operating System: Windows 10 (amd64) version 10.0

Java Version: 1.8.0_73, Oracle Corporation

Java VM Version: Java HotSpot 64-Bit Server VM (mixed mode), Oracle Corporation

Memory: 626505336 bytes (597 MB) / 1038876672 bytes (990 MB) up to 1038876672 bytes (990 MB)

JVM Flags: 3 total; -Xincgc -Xmx1024M -Xms1024M

AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used

IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94

FML: MCP v9.05 FML v7.10.99.99 Minecraft Forge 10.13.4.1614 4 mods loaded, 4 mods active

States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

UCHIJAAAAAAAAA mcp{9.05} [Minecraft Coder Pack] (minecraft.jar)

UCHIJAAAAAAAAA FML{7.10.99.99} [Forge Mod Loader] (forgeSrc-1.7.10-10.13.4.1614-1.7.10.jar)

UCHIJAAAAAAAAA Forge{10.13.4.1614} [Minecraft Forge] (forgeSrc-1.7.10-10.13.4.1614-1.7.10.jar)

UCHIJAAAAAAAAA xxxxxxxx{0.1} [xxxxxxxx] (bin)

GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.

Profiler Position: N/A (disabled)

Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used

Player Count: 1 / 8; [EntityPlayerMP['Player189'/19119, l='New Worldwq346g344v632v2453v', x=-73.43, y=72.00, z=185.88]]

Type: Integrated Server (map_client.txt)

Is Modded: Definitely; Client brand changed to 'fml,forge'

 

 

Any idea what could be causing it? It says "BlockBush" in the crash report somewhere but the crash tends to occur half a minute after breaking a dead bush, if I broke one.

[coolAlias]

If you read the docs for HarvestDropsEvent, you'll see that it specifically states that 'event.harvester' can be NULL, so you need to check for that.

[flamedragonX2]

Thanks. Unfortunately I don't know how to trigger the crash (it happens randomly quite occasionally), but I will try this.

 

Got any other checks that may be important?

[coolAlias]

Thanks. Unfortunately I don't know how to trigger the crash (it happens randomly quite occasionally), but I will try this.

It happens when a non-player causes blocks to drop, such as water flowing over crops or a creeper exploding (maybe the creeper counts as a harvester? it's been months since I've looked at the code).

[jeffryfisher]

Maybe put a torch next to a mushroom, or spread water through crops or carpets. Those actions may trigger the event without setting a "harvester".

 

If all else fails, try some TNT. It may not solve your problem, but it will make you feel better.

 

You may also temporarily wrap your danger zone in a try-catch frame. Catch the next NPE and output everything you can see. Try to figure out what was being harvested and how. Then you'll have a better idea how to replicate the NPE as needed during testing.

 

Looking at your call stack, it appears that something was acting upon a BlockBush.

 

Or you can simply accept CoolAlias's advice to check harvester for null.