#vulnerable code 
                                @Override
    public void parse(@Nullable Tokens source, ParserData data) {
        PandaScript script = data.getComponent(PandaComponents.PANDA_SCRIPT);
        ModuleLoader registry = script.getModuleLoader();

        Expression instance = null;
        ClassPrototype prototype;

        if (instanceSource != null) {
            String surmiseClassName = instanceSource.asString();
            prototype = registry.forClass(surmiseClassName).get();

            if (prototype == null) {
                instance = data.getComponent(PandaComponents.EXPRESSION).parse(data, instanceSource);
                prototype = instance.getReturnType();
            }
        }
        else {
            prototype = data.getComponent(ClassPrototypeComponents.CLASS_PROTOTYPE);
            instance = ThisExpressionCallback.asExpression(prototype);
        }

        ArgumentParser argumentParser = new ArgumentParser();
        Expression[] arguments = argumentParser.parse(data, argumentsSource);
        ClassPrototype[] parameterTypes = ExpressionUtils.toTypes(arguments);

        String methodName = methodNameSource.asString();
        PrototypeMethod prototypeMethod = prototype.getMethods().getMethod(methodName, parameterTypes);

        if (prototypeMethod == null) {
            throw new PandaParserFailure("Class " + prototype.getClassName() + " does not have method " + methodName, data, methodNameSource);
        }

        if (!voids && prototypeMethod.isVoid()) {
            throw new PandaParserFailure("Method " + prototypeMethod.getMethodName() + " returns nothing", data, methodNameSource);
        }

        this.invoker = new MethodInvoker(prototypeMethod, instance, arguments);
    } 
                            #location 11 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public void parse(@Nullable Tokens source, ParserData data) {
        PandaScript script = data.getComponent(PandaComponents.PANDA_SCRIPT);
        ModuleLoader registry = script.getModuleLoader();

        Expression instance = null;
        ClassPrototype prototype;

        if (instanceSource != null) {
            String surmiseClassName = instanceSource.asString();
            ClassPrototypeReference reference = registry.forClass(surmiseClassName);
            prototype = reference != null ? reference.get() : null;

            if (prototype == null) {
                instance = data.getComponent(PandaComponents.EXPRESSION).parse(data, instanceSource);
                prototype = instance.getReturnType();
            }
        }
        else {
            prototype = data.getComponent(ClassPrototypeComponents.CLASS_PROTOTYPE);
            instance = ThisExpressionCallback.asExpression(prototype);
        }

        ArgumentParser argumentParser = new ArgumentParser();
        Expression[] arguments = argumentParser.parse(data, argumentsSource);
        ClassPrototype[] parameterTypes = ExpressionUtils.toTypes(arguments);

        String methodName = methodNameSource.asString();
        PrototypeMethod prototypeMethod = prototype.getMethods().getMethod(methodName, parameterTypes);

        if (prototypeMethod == null) {
            throw new PandaParserFailure("Class " + prototype.getClassName() + " does not have method " + methodName, data, methodNameSource);
        }

        if (!voids && prototypeMethod.isVoid()) {
            throw new PandaParserFailure("Method " + prototypeMethod.getMethodName() + " returns nothing", data, methodNameSource);
        }

        this.invoker = new MethodInvoker(prototypeMethod, instance, arguments);
    }