Avoid warning message - Adding Database::num_rows

main/install/update-files-1.8.6.1-1.8.6.2.inc.php

@@ -61,6 +61,7 @@ if (defined('SYSTEM_INSTALLATION') || defined('DOKEOS_COURSE_UPDATE')) {
 	error_log('Getting courses for files updates: '.$sql, 0);
 	$result = Database::query($sql);
 	
+	if (Database::num_rows($result) > 0) {
 		while ($courses_directories = Database::fetch_array($result)) {
 			$currentCourseRepositorySys = $sys_course_path.$courses_directories['directory'].'/';
 			// upload > announcements
@@ -73,6 +74,7 @@ if (defined('SYSTEM_INSTALLATION') || defined('DOKEOS_COURSE_UPDATE')) {
 				mkdir($currentCourseRepositorySys."upload/announcements/images", $perm);
 			}
 		}
+	}
 	
 	//// Create a specific directory for global thumbails
 	// home > default_platform_document > template_thumb