App on android Studio keeps crashing. It is a simple CRUD app

Question

As the title suggests , the app is a simple crud app which keeps crashing after adding a card to it. The data is registered in the database(firebase) and the code is uploaded below along with the error.

FATAL EXCEPTION: main
    Process: com.example.cryptoapp, PID: 19360
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ProgressBar.setVisibility(int)' on a null object reference
        at com.example.cryptoapp.LoginActivity$2.onClick(LoginActivity.java:53)

The code for the login screen is as follows:

package com.example.cryptoapp;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.android.material.textfield.TextInputEditText;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;

public class LoginActivity extends AppCompatActivity {

    private TextInputEditText userNameEdt, pwdEdt;
    private Button loginBtn;
    private ProgressBar loadingPB;
    private TextView registerTV;
    private FirebaseAuth mAuth;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        userNameEdt = findViewById(R.id.idEdtUserName);
        pwdEdt = findViewById(R.id.idEdtPwd);
        loginBtn = findViewById(R.id.idBtnLogin);
        registerTV = findViewById(R.id.idTVRegister);
        mAuth = FirebaseAuth.getInstance();
        loadingPB = findViewById(R.id.idPBLoading);

        registerTV.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(LoginActivity.this, RegistrationActivity.class);
                startActivity(i);
            }
        });

        loginBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                loadingPB.setVisibility(View.VISIBLE);
                String userName = userNameEdt.getText().toString();
                String pwd = pwdEdt.getText().toString();
                if (TextUtils.isEmpty(userName) && TextUtils.isEmpty(pwd)) {
                    Toast.makeText(LoginActivity.this, "Please enter your details", Toast.LENGTH_SHORT).show();
                    return;
                } else {
                    mAuth.signInWithEmailAndPassword(userName, pwd).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task) {
                            if (task.isSuccessful()) {
                                loadingPB.setVisibility(View.GONE);
                                Toast.makeText(LoginActivity.this, "Login Successful", Toast.LENGTH_SHORT).show();
                                Intent i = new Intent(LoginActivity.this, MainActivity.class);
                                startActivity(i);
                                finish();
                            } else {
                                loadingPB.setVisibility(View.GONE);
                                Toast.makeText(LoginActivity.this, "Please Enter valid UserID and Password", Toast.LENGTH_SHORT).show();
                            }
                        }
                    });
                }
            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();
        FirebaseUser user = mAuth.getCurrentUser();
        if (user != null) {
            Intent i = new Intent(LoginActivity.this, MainActivity.class);
            startActivity(i);
            this.finish();
        }
    }
}

I'll provide the code for the main screen as well just for reference:

package com.example.cryptoapp;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.material.bottomsheet.BottomSheetDialog;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.squareup.picasso.Picasso;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity implements CryptoRVAdapter.CryptoClickInterface{

    private RecyclerView cryptoRV;
    private ProgressBar loadingPB;
    private FloatingActionButton addFAB;
    private FirebaseDatabase firebaseDatabase;
    private DatabaseReference databaseReference;
    private ArrayList<CryptoRVModal> cryptoRVModalArrayList ;
    private CryptoRVAdapter cryptoRVAdapter;
    private RelativeLayout bottomSheetRL;
    private FirebaseAuth mAuth;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        cryptoRV = findViewById(R.id.idRVCryptoes);
        loadingPB = findViewById(R.id.idPBLoading);
        addFAB = findViewById(R.id.idAddFAB);
        firebaseDatabase = FirebaseDatabase.getInstance();
        databaseReference = firebaseDatabase.getReference("Cryptoes");
        cryptoRVModalArrayList = new ArrayList<>();
        bottomSheetRL = findViewById(R.id.idRLBSheet);
        mAuth = FirebaseAuth.getInstance();
        cryptoRVAdapter = new CryptoRVAdapter(cryptoRVModalArrayList,this,this);
        cryptoRV.setLayoutManager(new LinearLayoutManager(this));
        cryptoRV.setAdapter(cryptoRVAdapter);
        addFAB.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                startActivity(new Intent(MainActivity.this,AddCryptoActivity.class));
            }
        });

        getAllCryptos();



    }

    private void getAllCryptos(){

        cryptoRVModalArrayList.clear();
        databaseReference.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) {
                loadingPB.setVisibility(View.GONE);
                cryptoRVModalArrayList.add(snapshot.getValue(CryptoRVModal.class));
                cryptoRVAdapter.notifyDataSetChanged();
            }

            @Override
            public void onChildChanged(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) {
                loadingPB.setVisibility(View.GONE);
                cryptoRVAdapter.notifyDataSetChanged();
            }

            @Override
            public void onChildRemoved(@NonNull DataSnapshot snapshot) {
                loadingPB.setVisibility(View.GONE);
                cryptoRVAdapter.notifyDataSetChanged();
            }

            @Override
            public void onChildMoved(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) {
                loadingPB.setVisibility(View.GONE);
                cryptoRVAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {

            }
        });
    }

    @Override
    public void onCryptoClick(int position) {
        displayBottomSheet(cryptoRVModalArrayList.get(position));
    }
    private void displayBottomSheet(CryptoRVModal cryptoRVModal) {
        final BottomSheetDialog bottomSheetDialog = new BottomSheetDialog(this);
        View layout = LayoutInflater.from(this).inflate(R.layout.bottom_sheet_dialog,bottomSheetRL);
        bottomSheetDialog.setContentView(layout);
        bottomSheetDialog.setCancelable(false);
        bottomSheetDialog.setCanceledOnTouchOutside(true);
        bottomSheetDialog.show();

        TextView cryptoNameTV = layout.findViewById(R.id.idTVCryptoName);
        TextView cryptoDescTV = layout.findViewById(R.id.idTVDescription);
        TextView cryptoPriceTV = layout.findViewById(R.id.idTVPrice);
        ImageView cryptoIV = layout.findViewById(R.id.idIVCrypto);
        Button editBtn = layout.findViewById(R.id.idBtnEdit);
        Button viewDetailsBtn = layout.findViewById(R.id.idBtnViewDetails);


        cryptoNameTV.setText(cryptoRVModal.getCryptoName());
        cryptoDescTV.setText(cryptoRVModal.getCryptoDescription());
        cryptoPriceTV.setText("Rs." + cryptoRVModal.getCryptoPrice());
        Picasso.get().load(cryptoRVModal.getCryptoImg()).into(cryptoIV);


        editBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(MainActivity.this, EditCryptoActivity.class);
                i.putExtra("crypto", cryptoRVModal);
                startActivity(i);
            }
        });
        viewDetailsBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(Intent.ACTION_VIEW);
                i.setData(Uri.parse(cryptoRVModal.getCryptoLink()));
                startActivity(i);
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main,menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        int id = item.getItemId();
        switch (id){
            case R.id.idLogOut:
                Toast.makeText(this, "User is Logged Out Successfully", Toast.LENGTH_SHORT).show();
                mAuth.signOut();
                Intent i = new Intent(MainActivity.this, LoginActivity.class);
                startActivity(i);
                this.finish();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}

Would really appreciate an input on this!!!