java.lang.NullPointerException: Attempt to invoke interface method \'java.lang.Object javax.script.ScriptEngine.eval(java.lang.String)\' on a null object reference

ScriptEngineManager mgr = new ScriptEngineManager();
ScriptEngine engine = mgr.getEngineByName(\"JavaScript\");
result = ((Double) engine.eval(currentaction));
display.setText(result.toString());

using UnityEngine;
using System.Collections;
public class PlayerController : MonoBehaviour {
public float walkSpeed = 2;
public float runSpeed = 6;
public float gravity = -12;
public float jumpHeight = 1;
[Range(0,1)]
public float airControlPercent;
public float turnSmoothTime = 0.2f;
float turnSmoothVelocity;
public float speedSmoothTime = 0.1f;
float speedSmoothVelocity;
float currentSpeed;
float velocityY;
Animator animator;
Transform cameraT;
public CharacterController controller;
void Start () {
   animator = GetComponent<Animator> ();
   cameraT = Camera.main.transform;
   controller = GetComponent<CharacterController> ();
}
void Update () {
   // input
   Vector2 input = new Vector2 (Input.GetAxisRaw (\"Horizontal\"), Input.GetAxisRaw (\"Vertical\"));
   Vector2 inputDir = input.normalized;
   bool running = Input.GetKey (KeyCode.LeftShift);
   Move (inputDir, running);
   if (Input.GetKeyDown (KeyCode.Space)) {
      Jump ();
   }
   // animator
   float animationSpeedPercent = ((running) ? currentSpeed / runSpeed : currentSpeed / walkSpeed * .5f);
   animator.SetFloat (\"speedPercent\", animationSpeedPercent, speedSmoothTime, Time.deltaTime);
}
void Move(Vector2 inputDir, bool running) {
   if (inputDir != Vector2.zero) {
      float targetRotation = Mathf.Atan2 (inputDir.x, inputDir.y) * Mathf.Rad2Deg + cameraT.eulerAngles.y;
      transform.eulerAngles = Vector3.up * Mathf.SmoothDampAngle(transform.eulerAngles.y, targetRotation, ref turnSmoothVelocity, GetModifiedSmoothTime(turnSmoothTime));
   }
      
   float targetSpeed = ((running) ? runSpeed : walkSpeed) * inputDir.magnitude;
   currentSpeed = Mathf.SmoothDamp (currentSpeed, targetSpeed, ref speedSmoothVelocity, GetModifiedSmoothTime(speedSmoothTime));
   velocityY += Time.deltaTime * gravity;
   Vector3 velocity = transform.forward * currentSpeed + Vector3.up * velocityY;
   controller.Move (velocity * Time.deltaTime);
   currentSpeed = new Vector2 (controller.velocity.x, controller.velocity.z).magnitude;
   if (controller.isGrounded) {
      velocityY = 0;
   }
}
void Jump() {
   if (controller.isGrounded) {
      float jumpVelocity = Mathf.Sqrt (-2 * gravity * jumpHeight);
      velocityY = jumpVelocity;
      animator.Play(\"JUMP00\");
   }
}
float GetModifiedSmoothTime(float smoothTime) {
   if (controller.isGrounded) {
      return smoothTime;
   }
   if (airControlPercent == 0) {
      return float.MaxValue;
   }
   return smoothTime / airControlPercent;
}
}

<?php 

require_once(\'libcurlemu.inc.php\');
 
$title = \'valami - Teszt\';
    $message = \'Valaki tett valamit és neked ezt tudnod kell!\';
    $url = \'http://*censored*\'
    $apiToken = \'*api key*\';
    $curlUrl = \'https://pushcrew.com/api/v1/send/all\';
    
    //set POST variables
    $fields = array(
      \'title\' => $title,
      \'message\' => $message,
      \'url\' => $url
    );
    $httpHeadersArray = Array();
    $httpHeadersArray[] = \'Authorization: key=\'.$apiToken;
    //open connection
    $ch = curl_init();
    //set the url, number of POST vars, POST data
    curl_setopt($ch, CURLOPT_URL, $curlUrl);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($fields));
    curl_setopt($ch, CURLOPT_HTTPHEADER, $httpHeadersArray);
    //execute post
    $result = curl_exec($ch);
    $resultArray = json_decode($result, true);
    if($resultArray[\'status\'] == \'success\') {
        //success
        echo $resultArray[\'request_id\']; //ID of Notification Request
    }
    else if($resultArray[\'status\'] == \'failure\') {
        //failure
        echo \'failure\';
    }
    else {
        //failure
        echo \'failure\';
    }
 
?>

<?php
// CURL Extension Emulation Library Example
//
// Usage should be straightforward; you simply use this script exactly as you
// would normally use the PHP CURL extension functions.
// first, include libcurlemu.inc.php
require_once(\'libcurlemu.inc.php\');
// at this point, libcurlemu has detected the best available CURL solution
// (either the CURL extension, if available, or the CURL commandline binary,
// if available, or as a last resort, HTTPRetriever, our native-PHP HTTP
// client implementation) and has implemented the curl_* functions if
// necessary, so you can use CURL normally and safely assume that all CURL
// functions are available.
// the rest of this example code is copied straight from the PHP manual\'s
// reference for the curl_init() function, and will work fine with libcurlemu
// create a new CURL resource
$ch = curl_init();
// set URL and other appropriate options
curl_setopt($ch, CURLOPT_URL, \"http://www.example.com/\");
curl_setopt($ch, CURLOPT_HEADER, false);
// grab URL and pass it to the browser
curl_exec($ch);
// close CURL resource, and free up system resources
curl_close($ch);
 
?>