Fixed issue #13778: Exporting data to the most recent version of R le…

…ads to incorrect data

application/core/plugins/ExportR/RSyntaxWriter.php

@@ -147,7 +147,7 @@ public function close()
                 $str .= '),labels=c(';
 
                 foreach ($answers as $answer) {
-                    $str .= '"'.addslashes($answer['value']).'", ';
+                    $str .= '"'.addslashes(!empty($answer['value'])?$answer['value']:$answer['code']).'", ';
                 }
 
                 $str = mb_substr($str, 0, -2);