Fix things according to some log samples from BTM Moon

* WorldClient.world sometimes is not ready when client receives packets.
  Now includes null safety check. Discard data when `world == null`.
* Replace NBT manipulation hack with custom `IElectricItemManager`.
  Inspired by IC2's debug tool.

src/main/java/frogcraftrebirth/common/item/ItemDecayBattery.java

@@ -25,57 +25,33 @@
 import java.util.List;
 
 import frogcraftrebirth.common.lib.item.ItemFrogCraft;
-import ic2.api.item.IElectricItem;
+import ic2.api.item.IElectricItemManager;
+import ic2.api.item.ISpecialElectricItem;
 import net.minecraft.client.resources.I18n;
 import net.minecraft.client.util.ITooltipFlag;
 import net.minecraft.creativetab.CreativeTabs;
+import net.minecraft.entity.EntityLivingBase;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.NonNullList;
 import net.minecraft.world.World;
 import net.minecraftforge.fml.relauncher.Side;
 import net.minecraftforge.fml.relauncher.SideOnly;
 
-public class ItemDecayBattery extends ItemFrogCraft implements IElectricItem {
-
+public class ItemDecayBattery extends ItemFrogCraft implements ISpecialElectricItem {
+
+	private static final IElectricItemManager DECAY_BATTERY_ELECTRIC_MANAGER = new DecayBatteryElectricManager();
+
 	public ItemDecayBattery(String name) {
 		super(false);
 		setMaxDamage(0);
 		setMaxStackSize(1);
 		setNoRepair();
 		setUnlocalizedName(name + "Battery.name");
 	}
-
-	@Override
-	public boolean canProvideEnergy(ItemStack itemStack) {
-		setCharge(itemStack);
-		return true;
-	}
-
-	@Override
-	public double getMaxCharge(ItemStack itemStack) {
-		setCharge(itemStack);
-		return 1;
-	}
 
 	@Override
-	public int getTier(ItemStack itemStack) {
-		setCharge(itemStack);
-		return 1;
-	}
-
-	@Override
-	public double getTransferLimit(ItemStack itemStack) {
-		setCharge(itemStack);
-		return 1;
-	}
-
-	private void setCharge(ItemStack stack) {
-		if (stack.hasTagCompound())
-			stack.getTagCompound().setInteger("charge", 1);
-		else {
-			stack.setTagCompound(new net.minecraft.nbt.NBTTagCompound());
-			stack.getTagCompound().setInteger("charge", 1);
-		}
+	public IElectricItemManager getManager(ItemStack itemStack) {
+		return DECAY_BATTERY_ELECTRIC_MANAGER; // BTM Moon: read & write NBT is expensive
 	}
 
 	@Override
@@ -92,4 +68,49 @@ public void getSubItems(CreativeTabs tab, NonNullList<ItemStack> list) {
 		}
 	}
 
+	private static final class DecayBatteryElectricManager implements IElectricItemManager {
+		@Override
+		public double charge(ItemStack itemStack, double v, int i, boolean b, boolean b1) {
+			return 0.0;
+		}
+
+		@Override
+		public double discharge(ItemStack itemStack, double v, int i, boolean b, boolean b1, boolean b2) {
+			return 1.0;
+		}
+
+		@Override
+		public double getCharge(ItemStack itemStack) {
+			return 1.0;
+		}
+
+		@Override
+		public double getMaxCharge(ItemStack itemStack) {
+			return 1.0;
+		}
+
+		@Override
+		public boolean canUse(ItemStack itemStack, double v) {
+			return true;
+		}
+
+		@Override
+		public boolean use(ItemStack itemStack, double v, EntityLivingBase entityLivingBase) {
+			return true;
+		}
+
+		@Override
+		public void chargeFromArmor(ItemStack itemStack, EntityLivingBase entityLivingBase) {}
+
+		@Override //Side note: there is no need to translate - EU is the symbol of IC2 electricity unit
+		public String getToolTip(ItemStack itemStack) {
+			return "1 /1 EU";
+		}
+
+		@Override
+		public int getTier(ItemStack itemStack) {
+			return 1;
+		}
+	}
+
 }

src/main/java/frogcraftrebirth/common/network/PacketFrog00TileUpdate.java

@@ -28,6 +28,7 @@
 
 import frogcraftrebirth.common.lib.tile.TileFrog;
 import net.minecraft.client.Minecraft;
+import net.minecraft.client.multiplayer.WorldClient;
 import net.minecraft.tileentity.TileEntity;
 import net.minecraft.util.math.BlockPos;
 import net.minecraftforge.fml.relauncher.Side;
@@ -56,7 +57,12 @@ public void writeData(DataOutputStream output) throws IOException {
 	@Override
 	public void readData(DataInputStream input) throws IOException {
 		BlockPos aPos = new BlockPos(input.readInt(), input.readInt(), input.readInt());
-		TileEntity tile = Minecraft.getMinecraft().world.getTileEntity(aPos);
+		WorldClient world = Minecraft.getMinecraft().world;
+		if (world == null) {
+			return; // BTM Moon: you will understand that this is possible during joining server
+		}
+
+		TileEntity tile = world.getTileEntity(aPos);
 
 		if (tile instanceof IFrogNetworkObject)
 			((IFrogNetworkObject) tile).readPacketData(input);