Instead of the WIP/prototyped `Portal.open_context()` offering
a `pld_spec` input arg, this changes to a proper decorator API for
specifying the "payload spec" on `@context` endpoints.
The impl change details actually cover 2-birds:
- monkey patch decorated functions with a new
`._tractor_context_meta: dict[str, Any]` and insert any provided input
`@context` kwargs: `_pld_spec`, `enc_hook`, `enc_hook`.
- use `inspect.get_annotations()` to scan for a `func` arg
type-annotated with `tractor.Context` and use the name of that arg as
the RPC task-side injected `Context`, thus injecting the needed arg
by type instead of by name (a longstanding TODO); raise a type-error
when not found.
- pull the `pld_spec` from the `._tractor_context_meta` attr both in the
`.open_context()` parent-side and child-side `._invoke()`-cation of
the RPC task and use the `msg._ops.maybe_limit_plds()` API to apply it
internally in the runtime for each case.
`RemoteActorError`s show this by default in their `.__repr__()`, and we
obvi capture and embed the src traceback in an `Error` msg prior to
transit, but for logging it's also handy to see the tb of any set
`Context._remote_error` on console especially when trying to decipher
remote error details at their origin actor. Also improve the log message
description using `ctx.repr_state` and show any `ctx.outcome`.
Longer run we don't want `tractor` app devs having to call
`msg._ops.limit_plds()` from every child endpoint.. so this starts
a list of decorator API ideas and obviously ties in with an ideal final
API design that will come with py3.13 and typed funcs. Obviously this
is directly fueled by,
- https://github.com/goodboy/tractor/issues/365
Other,
- type with direct `trio.lowlevel.Task` import.
- use `log.exception()` to show tbs for all error-terminations in
`.open_context()` (for now) and always explicitly mention the `.side`.
Hopefully would make grok-ing this fairly sophisticated sub-sys possible
for any up-and-coming `tractor` hacker
XD
A lot of internal API and re-org ideas I discovered/realized as part of
finishing the `__pld_spec__` and multi-threaded support. Particularly
better isolation between root-actor vs subactor task APIs and generally
less globally-state-ful stuff like `DebugStatus` and `Lock` method APIs
would likely make a lot of the hard to follow edge cases more clear?
Functionally working for multi-threaded (via cpython threads spawned
from `to_trio.to_thread.run_sync()`) alongside subactors, tested (for
now) only with threads started inside the root actor (which seemed to
have the most issues in terms of the impl and special cases..) using the
new `tractor.pause_from_sync()` API!
Main implementation changes to `.pause_from_sync()`
------ - ------
- from the root actor, we need to ensure bg thread case is handled
*specially* since no IPC is used to request the TTY stdio mutex and
`Lock` (API) usage is conducted entirely from a local task or thread;
dedicated `Lock` usage for the root-actor already is branched inside
`._pause()` and needs similar handling from a root bg-thread:
|_for the special case of a root bg thread we need to
`trio`-main-thread schedule a bg task inside a new
`_pause_from_bg_root_thread()`. The new task needs to implement most
of what was is handled inside `._pause()` manually, mostly because in
this root-actor-bg-thread case we have 2 constraints:
1. to enter `PdbREPL.interaction()` **from the bg thread** directly,
2. the task that `Lock._debug_lock.acquire()`s has to be the same
that calls `.release() (a `trio.FIFOLock` constraint)
|_impl deats of this `_pause_from_bg_root_thread()` include:
- (for now) calling `._pause()` to acquire the `Lock._debug_lock`.
- setting its own `DebugStatus.repl_release`.
- calling `.DebugStatus.shield_sigint()` to ensure the root's
main thread uses the right handler when the bg one is REPL-ing.
- wait manually on the `.repl_release()` to be set by the thread's
dedicated `PdbREPL` exit.
- manually calling `Lock.release()` from the **same task** that
acquired it.
- expect calls to `._pause()` to deliver a `tuple[Task, PdbREPL]` such
that we always get the handle both to any newly created REPl instance
and the (maybe) the scheduled bg task within which is runs.
- add a single `message: str` style to `log.devx()` based on branching
style for logging.
- ensure both `DebugStatus.repl` and `.repl_task` are set **just
before** calling `._set_trace()` to ensure the correct `Task|Thread`
is set when the REPL is finally entered from sync code.
- add a wrapping caller `_sync_pause_from_builtin()` which passes in the
new `called_from_builtin=True` to indicate `breakpoint()` caller
usage, obvi pass in `api_frame`.
Changes to `._pause()` in support of ^
------ - ------
- `TaskStatus.started()` and return the `tuple[Task, PdbREPL]` to
callers / starters.
- only call `DebugStatus.shield_sigint()` when no `repl` passed bc some
callers (like bg threads) may need to apply it at some specific point
themselves.
- tweak some asserts for the `debug_func == None` / non-`trio`-thread
case.
- add a mod-level `_repl_fail_msg: str` to be used when there's an
internal `._pause()` failure for testing, easier to pexpect match.
- more comprehensive logging for the root-actor branched case to
(attempt to) indicate any of the 3 cases:
- remote ctx from subactor has the `Lock`,
- already existing root task or thread has it or,
- some kinda stale `.locked()` situation where the root has the lock
but we don't know why.
- for root usage, revert to always `await Lock._debug_lock.acquire()`-ing
despite `called_from_sync` since `.pause_from_sync()` was reworked to
instead handle the special bg thread case in the new
`_pause_from_bg_root_thread()` task.
- always do `return _enter_repl_sync(debug_func)`.
- try to report any `repl_task: Task|Thread` set by the caller
(particularly for the bg thread cases) as being the thread or task
`._pause()` was called "on behalf of"
Changes to `DebugStatus`/`Lock` in support of ^
------ - ------
- only call `Lock.release()` from `DebugStatus.set_[quit/continue]()`
when called from the main `trio` thread and always call
`DebugStatus.release()` **after** to ensure `.repl_released()` is set
**after** `._debug_lock.release()`.
- only call `.repl_release.set()` from `trio` thread otherwise use
`.from_thread.run()`.
- much more refinements in `Lock.release()` for threading cases:
- return `bool` to indicate whether lock was released by caller.
- mask (in prep to drop) `_pause()` usage of
`Lock.release.force=True)` since forcing a release can't ever avoid
the RTE from `trio`.. same task **must** acquire/release.
- don't allow usage from non-`trio`-main-threads, ever; there's no
point since the same-task-needs-to-manage-`FIFOLock` constraint.
- much more detailed logging using `message`-building-style for all
caller (edge) cases.
|_ use a `we_released: bool` to determine failed-to-release edge
cases which can happen if called from bg threads, ensure we
`log.exception()` on any incorrect usage resulting in release
failure.
|_ complain loudly if the release fails and some other task/thread
still holds the lock.
|_ be explicit about "who" (which task or thread) the release is "on
behalf of" by reading `DebugStatus.repl_task` since the caller
isn't the REPL operator in many sync cases.
- more or less drop `force` support, as mentioned above.
- ensure we unset `._owned_by_root` if the caller is a root task.
Other misc
------ - ------
- rename `lock_tty_for_child()` -> `lock_stdio_for_peer()`.
- rejig `Lock.repr()` to show lock and event stats.
- stage `Lock.stats` and `.owner` methods in prep for doing a singleton
instance and `@property`s.
Originally discovered as while using `tractor.pause_from_sync()`
from the `i3ipc` client running in a bg-thread that uses `asyncio`
inside `modden`.
Turns out we definitely aren't correctly handling `.pause_from_sync()`
from the root actor when called from a `trio.to_thread.run_sync()`
bg thread:
- root-actor bg threads which can't `Lock._debug_lock.acquire()` since
they aren't in `trio.Task`s.
- even if scheduled via `.to_thread.run_sync(_debug._pause)` the
acquirer won't be the task/thread which calls `Lock.release()` from
`PdbREPL` hooks; this results in a RTE raised by `trio`..
- multiple threads will step on each other's stdio since cpython's GIL
seems to ctx switch threads on every input from the user to the REPL
loop..
Reproduce via reworking our example and test so that they catch and fail
for all edge cases:
- rework the `/examples/debugging/sync_bp.py` example to demonstrate the
above issues, namely the stdio clobbering in the REPL when multiple
threads and/or a subactor try to debug simultaneously.
|_ run one thread using a task nursery to ensure it runs conc with the
nursery's parent task.
|_ ensure the bg threads run conc a subactor usage of
`.pause_from_sync()`.
|_ gravely detail all the special cases inside a TODO comment.
|_ add some control flags to `sync_pause()` helper and don't use
`breakpoint()` by default.
- extend and adjust `test_debugger.test_pause_from_sync` to match (and
thus currently fail) by ensuring exclusive `PdbREPL` attachment when
the 2 bg root-actor threads are concurrently interacting alongside the
subactor:
|_ should only see one of the `_pause_msg` logs at a time for either
one of the threads or the subactor.
|_ ensure each attaches (in no particular order) before expecting the
script to exit.
Impl adjustments to `.devx._debug`:
- drop `Lock.repl`, no longer used.
- add `Lock._owned_by_root: bool` for the `.ctx_in_debug == None`
root-actor-task active case.
- always `log.exception()` for any `._debug_lock.release()` ownership
RTE emitted by `trio`, like we used to..
- add special `Lock.release()` log message for the stale lock but
`._owned_by_root == True` case; oh yeah and actually
`log.devx(message)`..
- rename `Lock.acquire()` -> `.acquire_for_ctx()` since it's only ever
used from subactor IPC usage; well that and for local root-task
usage we should prolly add a `.acquire_from_root_task()`?
- buncha `._pause()` impl improvements:
|_ type `._pause()`'s `debug_func` as a `partial` as well.
|_ offer `called_from_sync: bool` and `called_from_bg_thread: bool`
for the special case handling when called from `.pause_from_sync()`
|_ only set `DebugStatus.repl/repl_task` when `debug_func != None`
(OW ensure the `.repl_task` is not the current one).
|_ handle error logging even when `debug_func is None`..
|_ lotsa detailed commentary around root-actor-bg-thread special cases.
- when `._set_trace(hide_tb=False)` do `pdbp.set_trace(frame=currentframe())`
so the `._debug` internal frames are always included.
- by default always hide tracebacks for `.pause[_from_sync]()` internals.
- improve `.pause_from_sync()` to avoid root-bg-thread crashes:
|_ pass new `called_from_xxx_` flags and ensure `DebugStatus.repl_task`
is actually set to the `threading.current_thread()` when needed.
|_ manually call `Lock._debug_lock.acquire_nowait()` for the non-bg
thread case.
|_ TODO: still need to implement the bg-thread case using a bg
`trio.Task`-in-thread with an `trio.Event` set by thread REPL exit.
Exactly like how it's organized for `Portal.open_context()`, put the
main streaming API `@acm` with the `MsgStream` code and bind the method
to the new module func.
Other,
- rename `Context.result()` -> `.wait_for_result()` to better match the
blocking semantics and rebind `.result()` as deprecated.
- add doc-str for `Context.maybe_raise()`.
It ended up getting necessarily implemented as the `PldRx` though at
a different layer and won't be needed as part of `MsgCodec` most likely,
though this original idea did provide the source of inspiration for how
things work now!
Also Move the commented TODO proto for a codec hook factory from
`.types` to `._codec` where it prolly better fits and update some msg
related todo/questions.
It's been a long time prepped and now finally implemented!
Offer a `shield: bool` argument from our async `._debug` APIs:
- `await tractor.pause(shield=True)`,
- `await tractor.post_mortem(shield=True)`
^-These-^ can now be used inside cancelled `trio.CancelScope`s,
something very handy when introspecting complex (distributed) system
tear/shut-downs particularly under remote error or (inter-peer)
cancellation conditions B)
Thanks to previous prepping in a prior attempt and various patches from
the rigorous rework of `.devx._debug` internals around typed msg specs,
there ain't much that was needed!
Impl deats
- obvi passthrough `shield` from the public API endpoints (was already
done from a prior attempt).
- put ad-hoc internal `with trio.CancelScope(shield=shield):` around all
checkpoints inside `._pause()` for both the root-process and subactor
case branches.
Add a fairly rigorous example, `examples/debugging/shielded_pause.py`
with a wrapping `pexpect` test, `test_debugger.test_shield_pause()` and
ensure it covers as many cases as i can think of offhand:
- multiple `.pause()` entries in a loop despite parent scope
cancellation in a subactor RPC task which itself spawns a sub-task.
- a `trio.Nursery.parent_task` which raises, is handled and
tries to enter and unshielded `.post_mortem()`, which of course
internally raises `Cancelled` in a `._pause()` checkpoint, so we catch
the `Cancelled` again and then debug the debugger's internal
cancellation with specific checks for the particular raising
checkpoint-LOC.
- do ^- the latter -^ for both subactor and root cases to ensure we
can debug `._pause()` itself when it tries to REPL engage from
a cancelled task scope Bo
Keep the old alias, but i think it's better form to use longer names for
internal public APIs and this name better reflects the functionality:
decoding and returning a `PayloadMsg.pld` field.
Since turns out we didn't have a single example using that API Bo
The test granular-ly checks all use cases:
- `.post_mortem()` manual calls in both subactor and root.
- ensuring built-in RPC crash handling activates after each manual one
from ^.
- drafted some call-stack frame checking that i commented out for now
since we need to first do ANSI escape code removal due to the
colorization that `pdbp` does by default.
|_ added a TODO with SO link on `assert_before()`.
Also todo-staged a shielded-pause test to match with the already
existing-but-needs-refinement example B)
Such that we're boxing the interchanged lib's specific error
`msgspec.ValidationError` in this case) type much like how
a `ContextCancelled[trio.Cancelled]` is composed; allows for seemless
multi-backend-codec support later as well B)
Pass `ctx.maybe_raise(from_src_exc=src_err)` where needed in a couple
spots; as `None` in the send-side `Started` MTE case to avoid showing
the `._scope1.cancel_called` result in the traceback from the
`.open_context()` child-sync phase.
That is as a control to `Context._maybe_raise_remote_err()` such that
if set to anything other then the default (`False` value), we do
`raise remote_error from from_src_exc` such that caller can choose to
suppress or override the `.__cause__` tb.
Also tidy up and old masked TODO regarding calling `.maybe_raise()`
after the caller exits from the `yield` in `.open_context()`..
Send-side `MsgTypeError`s actually shouldn't have any "boxed" traceback
per say since they're raised in the transmitting actor's local task env
and we (normally) don't want the ascii decoration added around the
error's `._message: str`, that is not until the exc is `pack_error()`-ed
before transit. As such, the presentation of an embedded traceback (and
its ascii box) gets bypassed when only a `._message: str` is set (as we
now do for pld-spec failures in `_mk_msg_type_err()`).
Further this tweaks the `.pformat()` output to include the `._message`
part to look like `<RemoteActorError( <._message> ) ..` instead of
jamming it implicitly to the end of the embedded `.tb_str` (as was done
implicitly by `unpack_error()`) and also adds better handling for the
`with_type_header == False` case including forcing that case when we
detect that the currently handled exc is the RAE in `.pformat()`.
Toss in a lengthier doc-str explaining it all.
Surrounding/supporting changes,
- better `unpack_error()` message which just briefly reports the remote
task's error type.
- add public `.message: str` prop.
- always set a `._extra_msgdata: dict` since some MTE props rely on it.
- handle `.boxed_type == None` for `.boxed_type_str`.
- maybe pack any detected input or `exc.message` in `pack_error()`.
- comment cruft cleanup in `_mk_msg_type_err()`.
Allows passing a custom error msg other then the traceback-str over the
wire. Make `.tb_str` optional (in the blank `''` sense) since it's
treated that way thus far in `._exceptions.pack_error()`.
Namely checking that `Context._remote_error` is set to the raised MTE
in the invalid started and return value cases since prior to the recent
underlying changes to the `Context.result()` impl, it would not match.
Further,
- do asserts for non-MTE raising cases in both the parent and child.
- add todos for testing ctx-outcomes for per-side-validation policies
i anticipate supporting and implied msg-dialog race cases therein.
More specifically, if `.open_context()` is cancelled when awaiting the
first `Context.started()` during the child task sync phase, check to see
if it was due to `._scope.cancel_called` and raise any remote error via
`.maybe_raise()` instead the `trio.Cancelled` like in every other
remote-error handling case. Ensure we set `._scope[_nursery]` only after
the `Started` has arrived and audited.
Since in the case of the `Actor._cancel_task()` related runtime eps we
actually don't EVER register them in `Actor._rpc_tasks`.. logging about
them is just needless noise, though maybe we should track them in a diff
table; something like a `._runtime_rpc_tasks`?
Drop the cancel-request-for-stale-RPC-task (`KeyError` case in
`Actor._cancel_task()`) log-emit level in to `.runtime()`; it's
generally not useful info other then for granular race condition eval
when hacking the runtime.
So when `is_started_send_side is True` we raise the newly created
`MsgTypeError` (MTE) directly instead of doing all the `Error`-msg pack
and unpack to raise stuff via `_raise_from_unexpected_msg()` since the
raise should happen send side anyway and so doesn't emulate any remote
fault like in a bad `Return` or `Started` without send-side pld-spec
validation.
Oh, and proxy-through the `hide_tb: bool` input from `.drain_to_final_msg()`
to `.recv_msg_w_pld()`.
By calling `Context._maybe_cancel_and_set_remote_error(exc)` on any
unpacked `Error` msg; provides for `Context.maybe_error` consistency to
match all other error delivery cases.
Filling out the helper `validate_payload_msg()` staged in a prior commit
and adjusting all imports to match.
Also add a `raise_mte: bool` flag for potential usage where the caller
wants to handle the MTE instance themselves.
Expecting `Started` or `Return` with respective bad `.pld` values
depending on what type of failure is test parametrized.
This makes the suite run green it seems B)
The `TypeAlias` for the msg type-group is now `MsgType` and any user
touching shuttle messages can now be typed as `PayloadMsg`.
Relatedly, add MTE specific `Error._bad_msg[_as_dict]` fields which are
handy for introspection of remote decode failures.
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`.
In the sense that we handle it as a special case that exposed
through to `RxPld.dec_msg()` with a new `is_started_send_side: bool`.
(Non-ideal) `Context.started()` impl deats:
- only do send-side pld-spec validation when a new `validate_pld_spec`
is set (by default it's not).
- call `self.pld_rx.dec_msg(is_started_send_side=True)` to validate the
payload field from the just codec-ed `Started` msg's `msg_bytes` by
passing the `roundtripped` msg (with it's `.pld: Raw`) directly.
- add a `hide_tb: bool` param and proxy it to the `.dec_msg()` call.
(Non-ideal) `PldRx.dec_msg()` impl deats:
- for now we're packing the MTE inside an `Error` via a manual call to
`pack_error()` and then setting that as the `msg` passed to
`_raise_from_unexpected_msg()` (though really we should just raise
inline?).
- manually set the `MsgTypeError._ipc_msg` to the above..
Other,
- more comprehensive `Context` type doc string.
- various `hide_tb: bool` kwarg additions through `._ops.PldRx` meths.
- proto a `.msg._ops.validate_payload_msg()` helper planned to get the
logic from this version of `.started()`'s send-side validation so as
to be useful more generally elsewhere.. (like for raising back
`Return` values on the child side?).
Warning: this commit may have been made out of order from required
changes to `._exceptions` which will come in a follow up!
Starts with some very basic cases:
- verify both subactor-as-child-ctx-task send side validation (failures)
as well as relay and raise on root-parent-side-task.
- wrap failure expectation cases that bubble out of `@acm`s with
a `maybe_expect_raises()` equiv wrapper with an embedded timeout.
- add `Return` cases including invalid by `str` and valid by a `None`.
Still ToDo:
- commit impl changes to make the bulk of this suite pass.
- adjust how `MsgTypeError`s format the local (`.started()`) send side
`.tb_str` such that we don't do a "boxed" error prior to
`pack_error()` being called normally prior to `Error` transit.
Related to the prior patch, re the new `with_type_header: bool`:
- in the `with_type_header == True` use case make sure we keep the first
`._message: str` line non-indented since it'll show just after the
header-line's type path with ':'.
- when `False` drop the `)>` `repr()`-instance style as well so that we
just get the ascii boxed traceback as though it's the error
message-`str` not the `repr()` of the error obj.
Other,
- hide `pack_from_raise()` call frame since it'll show in debug mode
crash handling..
- mk `MsgTypeError.from_decode()` explicitly accept and proxy an
optional `ipc_msg` and change `msgdict` to also be optional, only
reading out the `**extra_msgdata` when provided.
- expose a `_mk_msg_type_err(src_err_msg: Error|None = None,)` for
callers who which to inject a `._ipc_msg: Msgtype` to the MTE.
|_ add a note how we can't use it due to a causality-dilemma when pld
validating `Started` on the send side..
And IFF the `await wait_func(proc)` is cancelled such that we avoid
clobbering some subactor that might be REPL-ing even though its parent
actor is in the midst of (gracefully) cancelling it.
From both `open_root_actor()` and `._entry._trio_main()`.
Other `breakpoint()`-from-sync-func fixes:
- properly disable the default hook using `"0"` XD
- offer a `hide_tb: bool` from `open_root_actor()`.
- disable hiding the `._trio_main()` frame, bc pretty sure it doesn't
help anyone (either way) when REPL-ing/tb-ing from a subactor..?
Mostly the result of the `RemoteActorError.pformat()` and our
new `_pause/crash_msg: str`s which include the `trio.Task.__repr__()`
in the `log.pdb()` message.
Obvi use the `in_prompt_msg()` to accomplish where not used prior.
ToDo later:
-[ ] still some outstanding questions on how detailed inceptions
should look, eg. in `test_multi_nested_subactors_error_through_nurseries()`
|_maybe we should be more pedantic at checking `.src_uid` vs.
`.relay_uid` fields?
-[ ] staged a placeholder test for verifying correct call-stack frame on
crash handler REPL entry.
-[ ] also need a test to verify that you can't pause from an already paused actor task
such as can happen if you try to step through runtime code that has
a recurrent entry to `._debug.pause()`.
Call it `hide_runtime_frames()` and stick all the lines from the top of
the `._debug` mod in there along with a little `log.devx()` emission on
what gets hidden by default ;)
Other,
- fix ref-error where internal-error handler might trigger despite the
debug `req_ctx` not yet having init-ed, such that we don't try to
cancel or log about it when it never was fully created/initialize..
- fix assignment typo iniside `_set_trace()` for `task`.. lel
Such that when displaying with `.__str__()` we do not show the type
header (style) since normally python's raising machinery already prints
the type path like `'tractor._exceptions.RemoteActorError:'`, so doing
it 2x is a bit ugly ;p
In support,
- include `.relay_uid` in `RemoteActorError.extra_body_fields`.
- offer a `with_type_header: bool` to `.pformat()` and only put the
opening type path and closing `')>'` tail line when `True`.
- add `.is_inception() -> bool:` for an easy way to determine if the
error is multi-hop relayed.
- only repr the `'|_relay_uid=<uid>'` field when an error is an inception.
- tweak the invalid-payload case in `_mk_msg_type_err()` to explicitly
state in the `message` how the `any_pld` value does not match the `MsgDec.pld_spec`
by decoding the invalid `.pld` with an any-dec.
- allow `_mk_msg_type_err(**mte_kwargs)` passthrough.
- pass `boxed_type=cls` inside `MsgTypeError.from_decode()`.
Tyler Goodlet