#vulnerable code 
                                static SrcClass genClass(String fqn, ProgramNode programNode) {

        ClassNode classNode = programNode.getFirstChild(ClassNode.class);

        SrcClass clazz = new SrcClass(fqn, SrcClass.Kind.Class);

        String superClass = classNode.getSuperClass();
        if (superClass != null) {
            clazz.superClass(superClass);
        }
        clazz.imports(JavascriptClass.class)
          .imports( SourcePosition.class );

        clazz.addField(new SrcField("ENGINE", ScriptEngine.class)
                .modifiers(Modifier.STATIC)
                .initializer(new SrcRawExpression(("JavascriptClass.init(\"" + fqn + "\")"))));


        clazz.addField(new SrcField("_context", ScriptObjectMirror.class));

        addConstructor(clazz, classNode);
        addMethods(fqn, clazz, classNode);
        addProperties(fqn, clazz, classNode);

        return clazz;
    } 
                            #location 7 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                static SrcClass genClass(String fqn, ProgramNode programNode) {

        ClassNode classNode = programNode.getFirstChild(ClassNode.class);

        SrcClass clazz = new SrcClass(fqn, SrcClass.Kind.Class);
        clazz.addAnnotation(
          new SrcAnnotationExpression( SourcePosition.class )
            .addArgument( "url", String.class, programNode.getUrl().toString() )
            .addArgument( "feature", String.class, ManClassUtil.getShortClassName( fqn ) )
            .addArgument( "offset", int.class, classNode.getStart().getOffset() )
            .addArgument( "length", int.class, classNode.getEnd().getOffset() - classNode.getStart().getOffset() ) );

        String superClass = classNode.getSuperClass();
        if (superClass != null) {
            clazz.superClass(superClass);
        }
        clazz.imports(JavascriptClass.class)
          .imports( SourcePosition.class );

        clazz.addField(new SrcField("ENGINE", ScriptEngine.class)
                .modifiers(Modifier.STATIC)
                .initializer(new SrcRawExpression(("JavascriptClass.init(\"" + fqn + "\")"))));


        clazz.addField(new SrcField("_context", ScriptObjectMirror.class));

        addConstructor(clazz, classNode);
        addMethods(fqn, clazz, classNode);
        addProperties(fqn, clazz, classNode);

        return clazz;
    }