Adjusted return type for CI_DB_utility::backup to suggestions
diff --git a/system/database/DB_utility.php b/system/database/DB_utility.php
index 9eac2ec..57356ac 100644
--- a/system/database/DB_utility.php
+++ b/system/database/DB_utility.php
@@ -417,7 +417,7 @@
 			return gzencode($this->_backup($prefs));
 		}
 
-		return '';
+		return;
 	}
 
 }