#vulnerable code 
                                public static Object getFor(int status, Request request, Response response) {

        Object customRenderer = CustomErrorPages.getInstance().customPages.get(status);
        Object customPage;

        if (customRenderer instanceof String) {
            customPage = customRenderer;
        } else {
            try {
                customPage = ((Route) customRenderer).handle(request, response);
            } catch (Exception e) {
                customPage = status == 400 ? NOT_FOUND : INTERNAL_ERROR;
            }
        }

        return customPage;
    } 
                            #location 10 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public static Object getFor(int status, Request request, Response response) {

        Object customRenderer = CustomErrorPages.getInstance().customPages.get(status);
        Object customPage;

        customPage = status == 400 ? NOT_FOUND : INTERNAL_ERROR;

        if (customRenderer instanceof String) {
            customPage = customRenderer;
        } else if (customRenderer instanceof Route) {
            try {
                customPage = ((Route) customRenderer).handle(request, response);
            } catch (Exception e) {
                // customPage is already set to default error so nothing needed here
            }
        }

        return customPage;
    }