EEROR: org.json.JSONException: Value [] of type org.json.JSONArray cannot be converted to JSONObject

Java code:

import android.app.ProgressDialog;
import android.content.Intent;
import android.graphics.drawable.AnimationDrawable;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.Androtech.app.instagram.MainActivity;
import com.Androtech.app.instagram.R;
import com.Androtech.app.instagram.helper.SharedPrefrenceManger;
import com.Androtech.app.instagram.helper.URLS;
import com.Androtech.app.instagram.helper.VolleyHandler;
import com.Androtech.app.instagram.models.User;

import org.json.JSONException;
import org.json.JSONObject;

import java.util.HashMap;
import java.util.Map;

public class SignUpActivity extends AppCompatActivity {


    LinearLayout mLoginContainer;
    AnimationDrawable mAnimationDrawable;

    EditText email_et, username_et,password_et,password_confirm_et;
    Button  sign_up_btn;
    TextView go_to_login_btn;
    ProgressDialog mProgrssDialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sign_up);


        //Animation config
        mLoginContainer = (LinearLayout) findViewById(R.id.login_container);
        mAnimationDrawable = (AnimationDrawable) mLoginContainer.getBackground();
        mAnimationDrawable.setEnterFadeDuration(5000);
        mAnimationDrawable.setExitFadeDuration(2000);


        //login design varibales
        email_et = (EditText) findViewById(R.id.user_email);
        username_et = (EditText) findViewById(R.id.user_name);
        password_et = (EditText) findViewById(R.id.user_password);
        password_confirm_et = (EditText) findViewById(R.id.user_password_confirm);
        sign_up_btn =  (Button) findViewById(R.id.sign_up_btn);
        go_to_login_btn = (TextView) findViewById(R.id.go_to_login_btn);
        mProgrssDialog = new ProgressDialog(this);


        sign_up_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                register();
            }
        });

        go_to_login_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
                startActivity(new Intent(SignUpActivity.this,LoginActivity.class));
            }
        });


    }


    private void register(){


        mProgrssDialog.setTitle("Creating your account");
        mProgrssDialog.setMessage("Please wait....");
        mProgrssDialog.show();

        final String email = email_et.getText().toString();
        final String username = username_et.getText().toString();
        final String password = password_et.getText().toString();
        String password_confirm = password_confirm_et.getText().toString();


        if(!email.contains("@")){
            email_et.setError("This is not a valid email");
            email_et.requestFocus();
            mProgrssDialog.dismiss();
            return;
        }
        if(TextUtils.isEmpty(username)){
            username_et.setError("Please fill in this field");
            username_et.requestFocus();
            mProgrssDialog.dismiss();
            return;
        }

        if(TextUtils.isEmpty(password)){
            password_et.setError("Please fill in this field");
            password_et.requestFocus();
            mProgrssDialog.dismiss();
            return;
        }

        if(TextUtils.isEmpty(password_confirm)){
            password_confirm_et.setError("Please fill in this field");
            password_confirm_et.requestFocus();
            mProgrssDialog.dismiss();
            return;
        }

        if(!password.equals(password_confirm)){
            password_et.setError("Password charachters don't match!");
            password_et.requestFocus();
            mProgrssDialog.dismiss();
            return;

        }


        StringRequest stringRequest = new StringRequest(Request.Method.POST, URLS.sign_up_api,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {

                        try {
                            JSONObject jsonObject = new JSONObject(response);

                            if(!jsonObject.getBoolean("error")){
                                mProgrssDialog.dismiss();

                                JSONObject jsonObjectUser =  jsonObject.getJSONObject("user");

                                User user = new User(jsonObjectUser.getInt("id"),jsonObjectUser.getString("email"),jsonObjectUser.getString("username")
                                        ,jsonObjectUser.getString("image"));


                                //store user data inside sharedprefrences
                                SharedPrefrenceManger.getInstance(getApplicationContext()).storeUserData(user);


                                //let user in
                                finish();
                                startActivity(new Intent(SignUpActivity.this,MainActivity.class));

                            }else{

                                Toast.makeText(SignUpActivity.this,jsonObject.getString("message"),Toast.LENGTH_LONG).show();
                            }


                        }catch (JSONException e){
                            e.printStackTrace();
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Toast.makeText(SignUpActivity.this,error.getMessage(),Toast.LENGTH_LONG).show();
                        mProgrssDialog.dismiss();
                    }
                }


        ){

            @Override
            protected Map<String, String> getParams() throws AuthFailureError {
                Map<String,String> authenticationVariables = new HashMap<>();
                authenticationVariables.put("email",email);
                authenticationVariables.put("username",username);
                authenticationVariables.put("password",password);
                return  authenticationVariables;
            }
        };//end of string Request

        VolleyHandler.getInstance(getApplicationContext()).addRequetToQueue(stringRequest);

    }


    @Override
    protected void onResume() {
        super.onResume();

        if(mAnimationDrawable != null && !mAnimationDrawable.isRunning()){
            mAnimationDrawable.start();
        }
    }

    @Override
    protected void onPause() {
        super.onPause();

        if(mAnimationDrawable != null && mAnimationDrawable.isRunning()){
            mAnimationDrawable.stop();
        }
    }



    @Override
    protected void onStart() {
        super.onStart();

        boolean isUserLoggedIn = SharedPrefrenceManger.getInstance(getApplicationContext()).isUserLogggedIn();

        if (isUserLoggedIn) {
            startActivity(new Intent(SignUpActivity.this, MainActivity.class));
        } else {

        }
    }




}

Error

W/System.err: org.json.JSONException: Value [] of type org.json.JSONArray cannot be converted to JSONObject
W/System.err:     at org.json.JSON.typeMismatch(JSON.java:111)
W/System.err:     at org.json.JSONObject.<init>(JSONObject.java:163)
        at org.json.JSONObject.<init>(JSONObject.java:176)
        at com.Androtech.app.instagram.authentication.SignUpActivity$3.onResponse(SignUpActivity.java:142)
        at com.Androtech.app.instagram.authentication.SignUpActivity$3.onResponse(SignUpActivity.java:137)
W/System.err:     at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:78)
        at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)
        at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:106)
W/System.err:     at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:6524)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:451)
W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:888)

I am trying to implement a sign-up activity but the following error is given when signing up in the emulator. I have seen a solution that proposes me to edit the code as below.

JSONArray jsonarray = new JSONArray(strResponse);
for(int i=0; i < jsonarray.length(); i++) {
    JSONObject jsonobject = jsonarray.getJSONObject(i);

I however do not know how to implement the proposed code together with my code:

if(!jsonObject.getBoolean("error")){
                                mProgrssDialog.dismiss();

                                JSONObject jsonObjectUser =  jsonObject.getJSONObject("user");

                                User user = new User(jsonObjectUser.getInt("id"),jsonObjectUser.getString("email"),jsonObjectUser.getString("username")
                                        ,jsonObjectUser.getString("image"));

Kindly help me figure out the code.