Remove notices

core/um-actions-register.php

@@ -274,6 +274,8 @@
 			$role = um_get_option('default_role');
 		}
 
+		if( empty( $role ) ) return;
+
 		$role = apply_filters('um_register_hidden_role_field', $role );
 		if( $role ){
 			echo '<input type="hidden" name="role" id="role" value="' . $role . '" />';