React Native Login connect with sql server ?

I posted a previous post and couldn't send the code, so this page reported an error so I resubmitted it

 When it's running, I enter user and password and press the login button, I get an error: ERROR Cannot convert null value to object

//App.js
import React, { useState } from 'react';
import { StyleSheet, View, TextInput, Button, FlatList, Text } from 'react-native';
import SQLite from 'react-native-sqlite-storage';
//import axios from 'axios';

const App = () => {
  // Kh?i t?o state s? luu tr? thông tin ngu?i dùng
  const [username, setUsername] = useState('');
  const [password, setPassword] = useState('');  
  const [sqliteData, setSqliteData] = useState([]); // Thêm 'sqliteData' vào danh sách các state


  // Hàm x? lý khi ngu?i dùng nh?n nút Login
  const handleLogin = async () => {
    //alert('login');
    //console.log('login1');
    try {
      // K?t n?i b?ng co s? d? li?u
      const db = SQLite.openDatabase(
        {          
          name: 'Cafe.db',
          location: 'default',
          //createFromLocation: '~www/test.db',
        },
        () => {
          console.log('Connected to the database.');
        },
        (error) => {
          console.error('Failed to connect to the database.', error);
        }
      );
            
      // Th?c hi?n truy v?n SQL s? lây d? li?u t? b?ng
      db.transaction(tx => {
        tx.executeSql(
          'SELECT * FROM TABUSERNAME',
          [],
          (_, result) => {
            if (result.rows) {
              const rows = result.rows.raw();
              setSqliteData(rows); // Luu tr? d? li?u t? SQLite vào state 'sqliteData'
            } else {
              console.log('No rows returned from the query.');
            }
          },
          error => {
            console.error('Failed to execute query.', error);
          }
        );
      });
      
      // Ðóng k?t n?i co s? d? li?u khi không s? d?ng n?a
      //return () => {
      db.close();
      console.log('Database connection closed.');
      //};

    } catch (error) {
      console.error(error.message);
    }
  };

   
  // Hàm x? lý khi ngu?i dùng nh?n nút Signup
  const handleSignup = async () => {
    try {
      //
    } catch (error) {
      console.error(error.message);
    }
  };
  

  return (
    
      
      
        {/* Hi?n th? d? li?u trong ô lu?i */}
         {JSON.stringify(item)}}
          keyExtractor={(_, index) => index.toString()}
        />
      
      
      
        
         
         {/* ngu?i dùng nh?p tên ngu?i dùng */}
            
         
         
            {/* ngu?i dùng nh?p m?t kh?u */}
            
         
        



        
          
              {/* Nút s? th?c hi?n ch?c nang dang nh?p */}
              
          
          
              {/* Nút s? th?c hi?n ch?c nang dang ký */}
              
          
        
      
         

      
    
  );
};

export default App;


const styles = StyleSheet.create({
  container: {
    flex : 1,
    backgroundColor : '#e7feff',      

  },
  flatlist: {
    //top : 340,
    //width : 50,
    //height : 50,
    backgroundColor : 'red',
  },
  inputText : {
    top: 340,    
    
  },
  text : {
    marginLeft : 30,
  },
  
  button : {
    width : 360,
    height : 150,
    marginHorizontal : 20,
    justifyContent : 'center',

  },
  login : {
    
  },

  signup : {
    top : 20,  
    },

  })

// server.js
const express = require('express');
const bodyParser = require('body-parser');
const sql = require('mssql');

const app = express();
const port = 3000;

app.use(bodyParser.json());

const config = {
  user: 'sa',
  password: '123456',
  server: 'MICROSOFT',
  database: 'Cafe',
  options: {
        encrypt: false // N?u không s? d?ng k?t n?i b?o m?t, d?t encrypt là false
      }
};

app.post('/login', async (req, res) => {
  const { username, password } = req.body;

  try {
      await sql.connect(dbConfig);

      const query = `SELECT * FROM TABUSERNAME WHERE USERNAME = @username AND PASSWORDS = @password`;
      const request = new sql.Request();
      request.input('username', sql.VarChar, username);
      request.input('password', sql.VarChar, password);
      
      const result = await request.query(query);

      if (result.recordset.length > 0) {
          res.json({ success: true, message: 'Login successful' });
      } else {
          res.status(401).json({ success: false, message: 'Login failed' });
      }
  } catch (err) {
      console.error('Database connection error', err);
      res.status(500).json({ success: false, message: 'Internal server error' });
  } finally {
      sql.close();
  }
});

/*
app.post('/login', async (req, res) => {
  try {
    await sql.connect(config);
    const result = await sql.query(`SELECT * FROM TABUSERNAME WHERE USERNAME='${req.body.username}' AND PASSWORDS='${req.body.password}'`);
    sql.close();
    res.json(result.recordset);
  } catch (error) {
    res.status(500).send(error.message);
  }
});
*/


app.listen(port, () => {
  console.log(`Server is running on port ${port}`);
});

1. Connection String:
   • Double-check the format and values of your connection string, ensuring they align with your SQL Server configuration.
   • Verify server name, instance name (if applicable), database name, authentication mode, and credentials.
2. Credentials:
   • Confirm that you're using the correct username and password for the SQL Server account.
3. Database Server Accessibility:
   • Ensure your application can reach the SQL Server instance on the specified network address or server name.
   • Check for firewall restrictions or network connectivity issues.
4. Table Name:

   Verify that the table name 'TABUSERNAME' is spelled correctly and exists in the 'Cafe' database.

   pen_spark

Share error details so we can understand the problem and find the solution for it.