Update build.xml - add a classpath to the manifest. This means the universal jar is now a server side launcher.

build.xml

@@ -173,6 +173,7 @@
     <jar destfile="${basedir}/target/${universal.jarname}.zip" duplicate="preserve">
       <manifest>
         <attribute name="Main-Class" value="net.minecraft.server.MinecraftServer"/>
+        <attribute name="Class-Path" value="minecraft_server.jar"/>
       </manifest>
       <fileset dir="${client.mcp.obfoutput}" includes="**/*.class" />
       <zipfileset dir="${basedir}" includes="fmlversion.properties"/>

eclipse/FML-MockMod/src/cpw/mods/mockmod/MockMod.java

@@ -76,6 +76,5 @@ public class MockMod
     public void init(FMLInitializationEvent evt)
     {
         System.out.printf("Hello from mockmod init : %s %s %s\n", myInstance, meta, MockBlock.tstInstance);
-        proxy.throwError();
     }
 }