Hi,  I was trying out the new stable version of Drools and on faulty DRL files I was getting: Exception in thread "main" java.lang.ArrayStoreException     at java.lang.System.arraycopy(Native Method)     at java.util.ArrayList.toArray(ArrayList.java:306)     at org.drools.compiler.PackageBuilder.getErrors(PackageBuilder.java:1274)     at org.drools.builder.impl.KnowledgeBuilderImpl.getErrors(KnowledgeBuilderImpl.java:70)     at com.arjun.SetGame.main(SetGame.java:18) The actual Error being:: (See Reference DRL at the end of this post) [Unable to resolve ObjectType 'MockBoolean' : [Rule name='show_time'] , Incorrect number of arguments for interval timer 'int 5s 2m'] I'd assume it be better to have an Exception with the root cause, than a faulty Error trapping system, that is trapping a System generated Exception. Is this a bug in "PackageBuilder : Line 1274"? Reference DRL: package com.arjun     rule show_time         timer (int 5s 2m)         when             MockBoolean(value == true)         then             System.out.println("Hey");     end