Form : do not use an error array if there is no error and the array is false

src/Form.php

@@ -613,7 +613,7 @@ class Form
             return $inputDate;
         }
         $errors = $date->getLastErrors();
-        if ($errors["warning_count"] > 0 || $errors["error_count"] > 0) {
+        if (is_array($errors) && ($errors["warning_count"] > 0 || $errors["error_count"] > 0)) {
             return $inputDate;
         }
         return $date->format($outputFormat);