Error: Undefined variable: conditional_defined

Notice: Undefined variable: conditional_defined in C:\xampp\www_root\ftp\classes\Htaccess.php on line 353

			global $dir;
			if ($other_conditional || $conditional_directory != '' && !self::matches($conditional_directory, $dir))
			//deal with <Directory> or an unknown < > tag
			{
				continue;
			}
			if ($conditional_defined != '')
			//deal with <IfDefine>
			{
				$conditional_defined = strtoupper($conditional_defined);
				if ($conditional_defined{0} === '!')
				{
					$conditional_defined = substr($conditional_defined, 1);
					if (defined($conditional_defined) && constant($conditional_defined))
					{
						continue;
					}
				}

$conditional_defined = ''