Such that if caught by user code and/or the runtime we can introspect
the original msg which caused the type error. Previously this was kinda
half-baked with a `.msg_dict` which was delivered from an `Any`-decode
of the shuttle msg in `_mk_msg_type_err()` but now this more explicitly
refines the API and supports both `PayloadMsg`-instance or the msg-dict
style injection:
- allow passing either of `bad_msg: PayloadMsg|None` or
`bad_msg_as_dict: dict|None` to `MsgTypeError.from_decode()`.
- expose public props for both ^ whilst dropping prior `.msgdict`.
- rework `.from_decode()` to explicitly accept `**extra_msgdata: dict`
|_ only overriding it from any `bad_msg_as_dict` if the keys are found in
`_ipcmsg_keys`, **except** for `_bad_msg` when `bad_msg` is passed.
|_ drop `.ipc_msg` passthrough.
|_ drop `msgdict` input.
- adjust `.cid` to only pull from the `.bad_msg` if set.
Related fixes/adjustments:
- `pack_from_raise()` should pull `boxed_type_str` from
`boxed_type.__name__`, not the `type()` of it.. also add a
`hide_tb: bool` flag.
- don't include `_msg_dict` and `_bad_msg` in the `_body_fields` set.
- allow more granular boxed traceback-str controls:
|_ allow passing a `tb_str: str` explicitly in which case we use it
verbatim and presume caller knows what they're doing.
|_ when not provided, use the more explicit
`traceback.format_exception(exc)` since the error instance is
a required input (we still fail back to the old `.format_exc()` call
if for some reason the caller passes `None`; but that should be
a bug right?).
|_ if a `tb: TracebackType` and a `tb_str` is passed, concat them.
- in `RemoteActorError.pformat()` don't indent the `._message` part used
for the `body` when `with_type_header == False`.
- update `_mk_msg_type_err()` to use `bad_msg`/`bad_msg_as_dict`
appropriately and drop passing `ipc_msg`.