JSFiddle - React, Tailwind, and code Playground

HTML

1) First the connect socket runs <b>line 43</b> <br/>
2) When the socket emits true the user searches for an ID.<b>line 59</b> <br/>
3) Error occurs at line 64 :<br/> <b>Error: Cannot enqueue Query after invoking quit.</b> <br/><br/>
4) A secondary error also displays for <b> Line 68</b>: <br/><b> db error { [Error: Cannot enqueue Quit after invoking quit.] code: 'PROTOCOL_ENQUEUE_AFTER_QUIT', fatal: false }
</b>

JavaScript

var http 	 = require('http'),
    fs           = require('fs'),
    sanitize 	 = require('validator').sanitize,
    mysql        = require('mysql');
	
var db_config = {
		host: '127.0.0.1',
		user: 'testDB',
		password: '[hidden]',
		database: '[hidden]'
};	

var clients = {},	
    connection;

connection = mysql.createConnection(db_config);
connection.connect(function(err) {              
   if(err) {   
     console.log('error when connecting to db:', err); 
   }                                     
});                                     

var app = http.createServer(function (request, response) {

fs.readFile(__dirname + 'client.html', 'utf-8', function (error, data) {
      if (error) {
	response.writeHead(500, {'Content-Type': 'text/html'});
	response.write(error.toString());
      } else {
	response.writeHead(200, {'Content-Type': 'text/html'});
	response.write(data);
      }
	response.end();
});


var io = require('socket.io').listen(app);

//connection
io.sockets.on('connection', function(socket) {
       
    //socket-connect
       socket.on('connect', function(data,callBack){
	       var session = sanitize(data['session']).escape();					
	   
           var query = connection.query('SELECT uid FROM sessions WHERE id = ?', [session],
	           function(err,results){
		       if(err){ 
                      console.log('Oh No! '+err);                   
                  }else{
  				      io.sockets.socket(socket.id).emit('connectConfirm',{data : true});
			      }
			      connection.end();
		       });
	   });
    //---//
    
    //socket-searchByID
	   socket.on('searchByID', function(data,callBack) {			
	       var userId = sanitize(data["userID"]).escape();
	       var query = connection.query('SELECT name FROM users U WHERE U.uid = ?', [userId],
			   function(err,results){
			   if(err){ 
			           console.log('Oh No! '+err);
			      } else if(results.length == 1){
				 	  io.sockets.emit("name",{ name: results[0].name});
			      }
			 ...