#fixed code
                                private Node getNodeByName(String name, StaplerResponse rsp) throws IOException {
        Jenkins jenkins = Jenkins.get();

        try {
            Node n = jenkins.getNode(name);

            if (n == null) {
                rsp.setStatus(SC_NOT_FOUND);
                rsp.setContentType("text/plain; UTF-8");
                rsp.getWriter().printf("A slave called '%s' does not exist.%n", name);
                return null;
            }
            return n;
        } catch (NullPointerException ignored) {}

        return null;
    }
#vulnerable code 
                                private Node getNodeByName(String name, StaplerResponse rsp) throws IOException {
        Jenkins jenkins = Jenkins.getInstance();

        try {
            Node n = jenkins.getNode(name);

            if (n == null) {
                rsp.setStatus(SC_NOT_FOUND);
                rsp.setContentType("text/plain; UTF-8");
                rsp.getWriter().printf("A slave called '%s' does not exist.%n", name);
                return null;
            }
            return n;
        } catch (NullPointerException ignored) {}

        return null;
    } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE