I was messing around with dispenser behaviour and found that if the dispenser is replaced/destroyed/otherwise removed while dispensing, the game crashes with this in the log:

Spoiler

PM
Description: Exception while ticking a block

java.lang.IllegalArgumentException: Cannot get property PropertyDirection{name=facing, clazz=class net.minecraft.util.EnumFacing, values=[down, up, north, south, west, east]} as it does not exist in BlockStateContainer{block=minecraft:air, properties=[]}
    at net.minecraft.block.state.BlockStateContainer$StateImplementation.getValue(BlockStateContainer.java:204)
    at net.minecraft.dispenser.BehaviorDefaultDispenseItem.dispense(BehaviorDefaultDispenseItem.java:18)
    at net.minecraft.block.BlockDispenser.dispense(BlockDispenser.java:153)
    at net.minecraft.block.BlockDispenser.updateTick(BlockDispenser.java:189)
    at net.minecraft.world.WorldServer.tickUpdates(WorldServer.java:774)
    at net.minecraft.world.WorldServer.tick(WorldServer.java:231)
    at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:825)
    at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:740)
    at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:589)
    at java.lang.Thread.run(Thread.java:748)

What happened to cause this is pretty simple - I made the dispensed stack cause an explosion, however, I get the same result if I set the dispenser to a different block (air, for example).
I have tried removing the tile entity before setting the block to air and/or causing the explosion, but the result is the same.

Is there any way I can prevent this crash, other than delaying the explosion?

Edited August 6, 20178 yr by PegBeard

I have a dispenser behaviour class, which is registered in the postInit:

 

Spoiler

public class DTDispensePowderKeg extends BehaviorDefaultDispenseItem
{
    @Override
	protected ItemStack dispenseStack(IBlockSource source, ItemStack stack)
    {
        World world = source.getWorld();
        BlockPos pos = source.getBlockPos();
        world.playSound((EntityPlayer)null, pos.getX(), pos.getY(), pos.getZ(), SoundEvents.ENTITY_TNT_PRIMED, SoundCategory.BLOCKS, 1.0F, 1.0F);
        stack.shrink(1);
        world.removeTileEntity(pos);
        world.isAirBlock(pos);
        world.newExplosion((EntityPlayer)null, pos.getX()+0.5D, pos.getY()+0.5D, pos.getZ()+0.5D, 4.0F, true, true);
        return stack;
    }
}

 

Is this correct? I looked it up back in 1.8, and assumed this was still relevant, as my other dispenser behaviours still work.

Oh. Is that something that changed since 1.8, or was the tutorial I followed back then wrong?

edit: the removeTileEntity was just testing for this issue, didn't intend to keep it.

Edited August 6, 20178 yr by PegBeard

11 minutes ago, PegBeard said:

Oh. Is that something that changed since 1.8, or was the tutorial I followed back then wrong?

Probably the latter.