Player Movement when phone shakes

So, I was trying to do a test where my game character can be moved using a joystick or a "shake" on the phone (the idea is that when the player walks around, the phone had a tilt and then, it's counted as a step in game). Maybe you can help me with the code. This code's objective is getting: 1 - The accelerometer input in y axis; 2 - The Joystick values; 3 - What I call "shaking routine"

So, the shaking routine happens when the accelerometer goes from the "low range" to the "high range" and then come back to the "low range". I made some tests and came with a low range from >0 and <1, the high range is any value >1 for the accelerometer input. For that, I've created a while structure, where it keeps comparing values from the accelerometer until finding the sequence that represents a shake.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class PlayerMovement : MonoBehaviour
 {
     protected Joystick joystick;
     public CharacterController controller;
     // Start is called before the first frame update
     void Start()
     {
         joystick = FindObjectOfType<Joystick>();
     }
 
     // Update is called once per frame
     void Update()
     {
         float accel;
         bool isShaking;
         int low;
         int high;
         accel = -Input.acceleration.y;
         low = 0;
         high = 0;
         Vector3 move = transform.right * joystick.Horizontal;
         isShaking = false;
         while (isShaking == false)
         {
             // Detect first movement
             if (accel < 1 && accel > 0) low++;
             // Detect second movement (only if first movement was detected)
             if (accel > 1 && low == 1) high++;
             // Detect a sequency of 1 low, 1 high and 1 low happen (2 low and 1 high)
             if (low == 2 && high == 1) isShaking = true;
             // If there was no sequence, do normal playermove
             move += transform.forward * joystick.Vertical;
             controller.Move(move * 10f * Time.deltaTime);
         }
         // Only if detected shaking sequence 
         move += transform.forward * 0.8f;
         controller.Move(move * 10f * Time.deltaTime);
     }
 }
 
 

But when I run this code, the engine crashes. What's wrong?