plugin XEP-0167: mapping adjustments: - use `9` as port placeholder - add `a=ice-options:trickle` to indicate that ICE candidates may be sent after SDP - moved senders mapping at media level - fix `rtpmap` channel setting - don't overwrite existing `fingerprint` data rel 424

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):
    ...