Давно все жалуются что при ошибках MySQL получаем пароли, набросал вот такую обертку, не претендую на уникальность, если у Вас есть замечания или предложения, всегда welcom =) 

mysqli.php

<?php
namespace DB;

final class MySQLi 
{
	private $connection;

	public function __construct( $hostname, $username, $password, $database, $port = '3306' ) 
	{
		try 
		{
			\mysqli_report( MYSQLI_REPORT_STRICT ); 
			
			$this->connection = new \mysqli( $hostname, $username, $password, $database, $port );
		
			$this->connection->set_charset( "utf8" );
			$this->connection->query( "SET SQL_MODE = ''" );
		} 
		catch ( \mysqli_sql_exception $e ) 
		{
			if ( \defined( 'IS_DEV' ) && IS_DEV ) 
			{
				throw $e;
			}
		}
	}

	public function query( $sql ) 
	{
		try 
		{
			if ( !\is_null($this->connection) ) 
			{
				$query = $this->connection->query( $sql );
			}
		}
		catch ( \mysqli_sql_exception $e ) 
		{
			if ( \defined( 'IS_DEV' ) && IS_DEV ) 
			{
				throw $e;
			}
		}		

		if ( !\is_null($this->connection) && !$this->connection->errno ) 
		{
			if ( $query instanceof \mysqli_result ) 
			{
				$data = array();

				while ( $row = $query->fetch_assoc() ) 
				{
					$data[] = $row;
				}

				$result = new \stdClass();

				$result->num_rows 	= $query->num_rows;
				$result->row 		= isset($data[0]) ? $data[0] : array();
				$result->rows 		= $data;

				$query->close();

				return $result;
			} 

			return true;
		}
	}

	public function escape($value) 
	{
		if ( !\is_null($this->connection) ) 
		{
			return $this->connection->real_escape_string($value);
		}

		return false;
	}
	
	public function countAffected() {
		if ( !\is_null($this->connection) ) 
		{
			return $this->connection->affected_rows;
		}

		return false;
	}

	public function getLastId() 
    {
		if ( !\is_null($this->connection) ) 
		{
			return $this->connection->insert_id;
		}

		return false;
	}
	
	public function connected() 
    {
		if ( !\is_null($this->connection) ) 
		{		
			return $this->connection->ping();
		}

		return false;
	}
	
	public function __destruct() 
    {
		if ( !\is_null($this->connection) ) 
		{
			$this->connection->close();
		}
	}
}