Clean up `._transport` error-case comment

Expand and clarify the comment for the default `case _`
block in the `.send()` error matcher, noting that we
console-error and raise-thru for unexpected disconnect
conditions.

(this patch was suggested by copilot in,
 https://github.com/goodboy/tractor/pull/411)

(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code

tractor/ipc/_transport.py

@@ -485,9 +485,11 @@ class MsgpackTransport(MsgTransport):
                         # await tractor.devx._trace.maybe_pause_bp()
                         raise tpt_closed from trans_err
 
-                    # unless the disconnect condition falls under "a
-                    # normal operation breakage" we usualy console warn
-                    # about it.
+                    # XXX, unless the disconnect condition falls
+                    # under "a normal/expected operating breakage"
+                    # (per the `trans_err_msg` guards in the cases
+                    # above) we usualy console-error about it and
+                    # raise-thru. about it.
                     case _:
                         log.exception(
                             f'{tpt_name} layer failed pre-send ??\n'