---
features:
  - |
    Improved error handling of custom request handlers. Request handlers added
    with ``respond_with_handler`` now can use the ``assert`` statement. Those
    errors will be reported when a further ``check_assertions()`` call is made.
    Also, unhandled exceptions raised in the request handlers can be re-raised
    by calling the new ``check_handler_errors()`` method. A new method called
    ``check()`` has been added which calls these two in sequence.
