Issue #2842326 - Fix validation

Closes #2842326

fapi_validation.module

@@ -65,8 +65,9 @@ function fapi_validation_filters_execute(&$element, &$form_state) {
 function fapi_validation_rules_execute(&$element, &$form_state) {
   $data = _fapi_validation_data('rules');
 
-  // If element is empty and not required, by pass rule validation
-  if (!$element['#required'] && empty($element['#value'])) {
+  // If element is empty and not required, bypass rule validation.
+  $no_value = !isset($element['#value']) || trim($element['#value']) == '';
+  if (!$element['#required'] && $no_value) {
     return;
   }