Missing assembly reference, What do I do?

I’m getting the error:
Assets/LeftDoorOpen_Close.cs(31,28): error CS1061: Type object' does not contain a definition for gameObject’ and no extension method gameObject' of type object’ could be found. Are you missing an assembly reference?

What do I do? Here is my code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class LeftDoorOpen_Close : MonoBehaviour {

Animator animator;
bool doorOpen;

public object LeftDoorKeyPad { get; private set; }

void Start()
{
    doorOpen = false;
    animator = GetComponent<Animator>();
}
void OnTriggerStay(Collider LeftDoorKeyPad)
{
    if(LeftDoorKeyPad.gameObject.tag == "Player")
    {
        if (Input.GetKey(KeyCode.X))
        {
            doorOpen = true;
            DropshipLeftDoor("Open");
        }
    }
}

void OnTriggerExit(Collider LeftDoorKeypad)
{
    if (LeftDoorKeyPad.gameObject.tag == "Player")      // <-- It's referring to this line.
    {
        if (Input.GetKey(KeyCode.X))
        {
            if (doorOpen)
            {
                doorOpen = false;
                DropshipLeftDoor("Close");
            }
        }
    }
}
   void DropshipLeftDoor(string direction)
{
    animator.SetTrigger(direction);
}

}

Sorry if this is a total noob question but I’m a beginner. :wink:

Try this:

 Animator animator;
     bool doorOpen;
     public GameObject LeftDoorKeyPad { get; private set; }
     void Start()
     {
         doorOpen = false;
         animator = GetComponent<Animator>();
     }
     void OnTriggerStay(Collider LeftDoorKeyPad)
     {
         if(LeftDoorKeyPad.gameObject.tag == "Player")
         {
             if (Input.GetKey(KeyCode.X))
             {
                 doorOpen = true;
                 DropshipLeftDoor("Open");
             }
         }
     }
     void OnTriggerExit(Collider LeftDoorKeypad)
     {
         if (LeftDoorKeyPad.tag == "Player")
         {
             if (Input.GetKey(KeyCode.X))
             {
                 if (doorOpen)
                 {
                     doorOpen = false;
                     DropshipLeftDoor("Close");
                 }
             }
         }
     }
        void DropshipLeftDoor(string direction)
     {
         animator.SetTrigger(direction);
     }