java.lang.NullPointerException
        at com.sun.tools.jdi.ReferenceTypeImpl.constantPool(ReferenceTypeImpl.java:1025)
        at sun.reflect.GeneratedMethodAccessor103.invoke(GeneratedMethodAccessor103.java:0)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
Caused: java.lang.IllegalStateException: java.lang.NullPointerException
        at org.netbeans.modules.debugger.jpda.jdi.ReferenceTypeWrapper.constantPool(ReferenceTypeWrapper.java:227)
        at org.netbeans.modules.debugger.jpda.ExpressionPool.createExpressionAt(ExpressionPool.java:168)
        at org.netbeans.modules.debugger.jpda.ExpressionPool.getExpressionAt(ExpressionPool.java:102)
        at org.netbeans.modules.debugger.jpda.actions.StepActionProvider.setLastOperation(StepActionProvider.java:462)
        at org.netbeans.modules.debugger.jpda.actions.StepActionProvider.setLastOperation(StepActionProvider.java:432)
        at org.netbeans.modules.debugger.jpda.actions.StepActionProvider.exec(StepActionProvider.java:318)
        at org.netbeans.modules.debugger.jpda.util.Operator$1.run(Operator.java:327)
        at java.lang.Thread.run(Thread.java:619)