plugin XEP-0234: fix action type when pre-flight file confirmation is confirmed: the `C.META_TYPE_FILE` can't be used in this case as it is a preflight and we don't have yet data such as progress ID. `C.META_TYPE_FILE` is used as a sub-type to help with dialog management in frontend.

from typing import Optional

from twisted.words.xish import domish


class BaseError(Exception):
    namespace: str
    condition: str
    text: Optional[str]
    textLang: Optional[str]
    appCondition: Optional[domish.Element]

class StanzaError(BaseError):
    ...