Issue #2149091 by torotil, grahamC | ardeso: Uploading Files produces JS error.

clientside_validation.module

@@ -1154,6 +1154,8 @@ function _clientside_validation_set_regex_pcre($name, $title, &$js_rules, $expre
  * Set validation rule for file fields that must have a certain extension.
  */
 function _clientside_validation_set_extensions($name, $extensions, &$js_rules) {
+  // @see https://drupal.org/comment/8428631#comment-8428631
+  /*
   $extension_list = preg_replace('#,(?![^,]+,)#', ' or', implode(', ', $extensions));
   $js_rules[$name]['accept'] = implode('|', $extensions);
   $variables = array(
@@ -1163,6 +1165,7 @@ function _clientside_validation_set_extensions($name, $extensions, &$js_rules) {
     'element_name' => $name
   );
   $js_rules[$name]['messages']['accept'] = theme('clientside_error', $variables);
+  */
 }
 
 /**