The base class ``ErrorList`` only has ``as_ul()``, which is overloaded. ``ErrorList.__str()__`` refers to ``as_ul()``.
``as_p()`` has been added for Bootstrap 3 layouts and is only used if called specifically. I am not sure if ``as_table()`` would be used at all.
Possibly a better, less specific approach would be to subclass ``TupleErrorList``, define ``as_p()`` there, add an argument to ``NgFormValidationMixin`` for overriding ``error_class`` on instantiation.