[bugfix] skip_validation_for_hidden_fields issue

Hi,

I have been experiencing an incompatibility between this plugin and the WP GDPR Compliance plugin: when CF7 conditional fields were enabled, the GDPR field stopped validating. Instead of being mandatory, users could proceed without accepting the checkbox.

After debugging with error_log I found out that the skip_validation_for_hidden_fields has a bug, it calls the invalidate method of the WPCF7_Validation object in a wrong way.

Here is my proposed fix, it seems to work. Instead of passing a string as the first argument of the invalidate method, I pass the corresponding WPCF7_FormTag object.

function skip_validation_for_hidden_fields($result, $tags, $args = []) {

        if(isset($_POST)) {
            $this->set_hidden_fields_arrays($_POST);
        }

        $invalid_fields = $result->get_invalid_fields();
        $return_result = new WPCF7_Validation();
		

        if (count($this->hidden_fields) == 0 || !is_array($invalid_fields) || count($invalid_fields) == 0) {
            $return_result = $result;
        } else {
            foreach ($invalid_fields as $invalid_field_key => $invalid_field_data) {
                if (!in_array($invalid_field_key, $this->hidden_fields)) {
                    // the invalid field is not a hidden field, so we'll add it to the final validation result
					foreach ($tags as $tag) {
						if ($tag->name == $invalid_field_key) {
							$return_result->invalidate($tag, $invalid_field_data['reason']);
						}
					}
                }
            }
        }

        return apply_filters('wpcf7cf_validate', $return_result, $tags);

    }