In kotlin I am making app to signUp, Login and then after successfull signIn user will be forwarded to home screen
where all users will be displayed, So I am fetching data from database to show in the recyclerView and getting this error :(
please help.

2022-03-24 10:38:46.835 9086-6305/? V/FA-SVC: Logging event: origin=auto,name=user_engagement(_e),params=Bundle[{ga_event_origin(_o)=auto, engagement_time_msec(_et)=11817, ga_screen_class(_sc)=SignUp, ga_screen_id(_si)=5165931126923283161}]
2022-03-24 10:38:46.925 2079-3402/? E/ActivityTrigger: activityResumeTrigger: not whiteListedcom.example.chatplusapp/com.example.chatplusapp.SignUp/1
2022-03-24 10:38:46.925 2079-3402/? E/ActivityTrigger: activityResumeTrigger: not whiteListedcom.example.chatplusapp/com.example.chatplusapp.SignUp/1
2022-03-24 10:38:56.753 9086-6305/? V/FA-SVC: Logging event: origin=auto,name=user_engagement(_e),params=Bundle[{ga_event_origin(_o)=auto, engagement_time_msec(_et)=9550, ga_screen_class(_sc)=SignUp, ga_screen_id(_si)=5165931126923283161}]
2022-03-24 10:38:56.772 9086-6305/? V/FA-SVC: Logging event: origin=auto,name=screen_view(_vs),params=Bundle[{ga_event_origin(_o)=auto, ga_previous_class(_pc)=SignUp, ga_previous_id(_pi)=5165931126923283161, ga_screen_class(_sc)=MainActivity, ga_screen_id(_si)=5165931126923283162}]

Here is my main activity code where fetch and display user data details into recyclerView adapter code is there.

package com.example.chatplusapp

import android.content.Intent
import android.os.Bundle
import android.view.Menu
import android.view.MenuItem
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.database.*

class MainActivity : AppCompatActivity() {

    private lateinit var userRecyclerView: RecyclerView
    private lateinit var userList: ArrayList<User>
    private lateinit var adapter: UserAdapter
    private lateinit var mAuth: FirebaseAuth
    private lateinit var mDbRef: DatabaseReference


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        mAuth= FirebaseAuth.getInstance()

        mDbRef= FirebaseDatabase.getInstance().getReference()



        userList= ArrayList()
        adapter= UserAdapter(this, userList)




        userRecyclerView= findViewById(R.id.userRecyclerView)
        userRecyclerView.layoutManager= LinearLayoutManager(this)
        userRecyclerView.adapter= adapter



        //read the value from the database
        mDbRef.child("user").addValueEventListener(object : ValueEventListener {
            override fun onDataChange(snapshot: DataSnapshot) {

                
                userList.clear()

                //snapshot is use to get how schema of the database is
                for (postSnapshot in snapshot.children) {
                    //create user object and add it to the user list
                    val currentUser = postSnapshot.getValue(User::class.java)

                    //if current user is there then dont display that to the list
                    if(mAuth.currentUser?.uid!=currentUser?.uid){
                        userList.add(currentUser!!)
                    }
                }
                
                adapter.notifyDataSetChanged()
            }

            override fun onCancelled(error: DatabaseError) {
                TODO("Not yet implemented")
            }

        })

    }

    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.menu_item, menu)
        return super.onCreateOptionsMenu(menu)
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        if(item.itemId==R.id.logout){
            //write the code for sign-out
            mAuth.signOut()
            startActivity(Intent(this@MainActivity, LogIn::class.java))
            finish()
            return true
        }
        return true
    }

}