Fixed type of db\Exception::$errorInfo

type is array in PHP documentation

framework/yii/db/Exception.php

@@ -16,19 +16,19 @@ namespace yii\db;
 class Exception extends \yii\base\Exception
 {
 	/**
-	 * @var mixed the error info provided by a PDO exception. This is the same as returned
+	 * @var array the error info provided by a PDO exception. This is the same as returned
 	 * by [PDO::errorInfo](http://www.php.net/manual/en/pdo.errorinfo.php).
 	 */
-	public $errorInfo;
+	public $errorInfo = array();
 
 	/**
 	 * Constructor.
 	 * @param string $message PDO error message
-	 * @param mixed $errorInfo PDO error info
+	 * @param array $errorInfo PDO error info
 	 * @param integer $code PDO error code
 	 * @param \Exception $previous The previous exception used for the exception chaining.
 	 */
-	public function __construct($message, $errorInfo = null, $code = 0, \Exception $previous = null)
+	public function __construct($message, $errorInfo = array(), $code = 0, \Exception $previous = null)
 	{
 		$this->errorInfo = $errorInfo;
 		parent::__construct($message, $code, $previous);