My mod works fine when run in the workspace, however, if I do gradlew.bat build, and use the compiled mod, it crashes, giving me the following report:

 

 

---- Minecraft Crash Report ----

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

 

Time: 3/9/14 9:37 PM

Description: Exception in server tick loop

 

java.lang.NoSuchMethodError: net.minecraft.util.DamageSource.getDamageType()Ljava/lang/String;

at f1repl4ce.MobRebirth.MobSpawningHandler.onEntityLivingDeath(MobSpawningHandler.java:25)

at cpw.mods.fml.common.eventhandler.ASMEventHandler_4_MobSpawningHandler_onEntityLivingDeath_LivingDeathEvent.invoke(.dynamic)

at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:51)

at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:122)

at net.minecraftforge.common.ForgeHooks.onLivingDeath(ForgeHooks.java:285)

at net.minecraft.entity.EntityLivingBase.func_70645_a(EntityLivingBase.java:934)

at net.minecraft.entity.EntityLivingBase.func_70097_a(EntityLivingBase.java:896)

at net.minecraft.entity.player.EntityPlayer.func_71059_n(EntityPlayer.java:1286)

at net.minecraft.network.NetHandlerPlayServer.func_147340_a(NetHandlerPlayServer.java:833)

at net.minecraft.network.play.client.C02PacketUseEntity.func_148833_a(SourceFile:55)

at net.minecraft.network.play.client.C02PacketUseEntity.func_148833_a(SourceFile:10)

at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:211)

at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:173)

at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:680)

at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:568)

at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:114)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:452)

at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:705)

 

 

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

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

 

-- System Details --

Details:

Minecraft Version: 1.7.2

Operating System: Windows 7 (x86) version 6.1

Java Version: 1.7.0_51, Oracle Corporation

Java VM Version: Java HotSpot Client VM (mixed mode, sharing), Oracle Corporation

Memory: 98817888 bytes (94 MB) / 209612800 bytes (199 MB) up to 518979584 bytes (494 MB)

JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M

AABB Pool Size: 4738 (265328 bytes; 0 MB) allocated, 4429 (248024 bytes; 0 MB) used

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

FML: MCP v9.01-pre FML v7.2.116.1024 Minecraft Forge 10.12.0.1024 4 mods loaded, 4 mods active

mcp{8.09} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

FML{7.2.116.1024} [Forge Mod Loader] (forge-1.7.2-10.12.0.1024.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

Forge{10.12.0.1024} [Minecraft Forge] (forge-1.7.2-10.12.0.1024.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

mobrebirth{1.1} [mobrebirth] ([1.7.2]MobRebirth2.0a.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

Profiler Position: N/A (disabled)

Vec3 Pool Size: 795 (44520 bytes; 0 MB) allocated, 557 (31192 bytes; 0 MB) used

Player Count: 1 / 8; [EntityPlayerMP['The_Fireplace'/268, l='Mob Rebirth Test', x=-486.20, y=4.00, z=-160.40]]

Type: Integrated Server (map_client.txt)

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

 

And here is my code:

 

 

package f1repl4ce.MobRebirth;

import cpw.mods.fml.common.eventhandler.SubscribeEvent;
import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityList;
import net.minecraft.entity.EntityLiving;
import net.minecraft.entity.monster.IMob;
import net.minecraft.entity.passive.IAnimals;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.projectile.EntityArrow;
import net.minecraft.init.Items;
import net.minecraft.item.Item;
import net.minecraft.item.ItemMonsterPlacer;
import net.minecraft.item.ItemStack;
import net.minecraft.world.World;
import net.minecraftforge.event.entity.living.LivingDeathEvent;
import net.minecraftforge.event.entity.living.LivingSpawnEvent;
import net.minecraft.entity.monster.*;

public class MobSpawningHandler {

@SubscribeEvent
public void onEntityLivingDeath(LivingDeathEvent event) {

	if (event.source.getDamageType().equals("player")) {//Checks to see if a player killed it
		EntityPlayer p = (EntityPlayer) event.source.getEntity();

			if ((event.entityLiving instanceof IMob)) {//Checks to see if it was a Mob
				double rand = Math.random();
				//rand = 0.0d;
				if (rand < HandlersInit.SPAWNMOBCHANCE) {//Checks the chance to see if anything should happen
					int id = EntityList.getEntityID(event.entityLiving);
					if (id > 0 && EntityList.entityEggs.containsKey(id)) {
						if (HandlersInit.SPAWNMOB = false){ //Checks to see if Mob spawning instead of Eggs is turned off
						ItemStack dropEgg = new ItemStack(
								Items.spawn_egg, 1, id); //sets what item should drop
						event.entityLiving.entityDropItem(dropEgg, 0.0F);}//Makes the item drop
						else{
							Entity entity = ItemMonsterPlacer.spawnCreature(event.entityLiving.worldObj , id, event.entityLiving.posX, event.entityLiving.posY, event.entityLiving.posZ);
						}


				}

			}
		}
			else
			if ((event.entityLiving instanceof IAnimals)) {//Checks to see if it was an Animal
				if (HandlersInit.SPAWNANIMALS = true){//Checks if Animal Spawning is enabled
				double rand = Math.random();
				//rand = 0.0d;
				if (rand < HandlersInit.SPAWNMOBCHANCE) {//Checks the chance to see if anything should happen
					int id = EntityList.getEntityID(event.entityLiving);
					if (id > 0 && EntityList.entityEggs.containsKey(id)) {
							if (HandlersInit.SPAWNMOB = false){ //Checks to see if Animal spawning instead of Eggs is turned off
								ItemStack dropEgg = new ItemStack(
										Items.spawn_egg, 1, id); //sets what item should drop
								event.entityLiving.entityDropItem(dropEgg, 0.0F);}//Makes the item drop
							else{
								Entity entity = ItemMonsterPlacer.spawnCreature(event.entityLiving.worldObj , id, event.entityLiving.posX, event.entityLiving.posY, event.entityLiving.posZ);
						}
						}


				}

			}
		}

	}

	if (event.source.getSourceOfDamage() instanceof EntityArrow) {
		if (((EntityArrow) event.source.getSourceOfDamage()).shootingEntity != null) {
			if (((EntityArrow) event.source.getSourceOfDamage()).shootingEntity instanceof EntityPlayer) {//checks to see if the arrow came from a player

				EntityPlayer p = (EntityPlayer) event.source.getEntity();


					if ((event.entityLiving instanceof IMob)) {//Checks to see if the entity was a mob
						double rand = Math.random();
						//rand = 0.0d;

						if (rand < HandlersInit.SPAWNMOBCHANCE) {//checks the chance to see if anything should happen
							int id = EntityList.getEntityID(event.entityLiving);
							if (id > 0
									&& EntityList.entityEggs.containsKey(id)) {//sets variable 'id', used to tell it which egg to drop
								     if (HandlersInit.SPAWNMOB = false) { //Checks to see if Mob spawning instead of Eggs is turned off
									ItemStack dropEgg = new ItemStack(Items.spawn_egg, 1, id);//sets what item will drop
								event.entityLiving.entityDropItem(dropEgg, 0.0F); }//drops the item
								     else{
										Entity entity = ItemMonsterPlacer.spawnCreature(event.entityLiving.worldObj , id, event.entityLiving.posX, event.entityLiving.posY, event.entityLiving.posZ);
										}

						}

					}

				}
					else
						if ((event.entityLiving instanceof IAnimals)) {//Checks to see if it was an Animal
							if (HandlersInit.SPAWNANIMALS = true){//Checks if Animal Spawning is enabled
							double rand = Math.random();
							//rand = 0.0d;
							if (rand < HandlersInit.SPAWNMOBCHANCE) {//Checks the chance to see if anything should happen
								int id = EntityList.getEntityID(event.entityLiving);
								if (id > 0 && EntityList.entityEggs.containsKey(id)) {
										if (HandlersInit.SPAWNMOB = false){ //Checks to see if Animal spawning instead of Eggs is turned off
											ItemStack dropEgg = new ItemStack(
													Items.spawn_egg, 1, id); //sets what item should drop
											event.entityLiving.entityDropItem(dropEgg, 0.0F);}//Makes the item drop
										else{
											Entity entity = ItemMonsterPlacer.spawnCreature(event.entityLiving.worldObj , id, event.entityLiving.posX, event.entityLiving.posY, event.entityLiving.posZ);
									}
									}


							}

						}
					}
			}

		}

	}

}
}

 

 

That might be a problem with reobfuscation then. Try running "gradlew --refresh-dependencies build" and see if that helps, or even re-run "gradlew setupDevWorkspace" before building.

 

On a side note, you can use event.source.getEntity() instanceof EntityPlayer as a more generic way to check if a player was the cause of damage, rather than only checking for damageType().equals("player"). The latter will not work for things like projectiles, while the former will.