Fix misc bugs caught by Copilot review

Deats,
- use `proc.poll() is None` in `sig_prog()` to
  distinguish "still running" from exit code 0;
  drop stale `breakpoint()` from fallback kill
  path (would hang CI).
- add missing `raise` on the `RuntimeError` in
  `async_main()` when no tpt bind addrs given.
- clean up stale uid entries from the registrar
  `_registry` when addr eviction empties the
  addr list.
- update `discovery.__init__` docstring to match
  the new eager `._multiaddr` import.
- fix `registar` -> `registrar` typo in teardown
  report log msg.

Review: PR #429 (Copilot)
https://github.com/goodboy/tractor/pull/429

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

tests/conftest.py

@@ -212,7 +212,7 @@ def sig_prog(
     '''
     for i in range(tries):
         proc.send_signal(sig)
-        if not proc.poll():
+        if proc.poll() is None:
             print(
                 f'WARNING, proc still alive after,\n'
                 f'canc_timeout={canc_timeout!r}\n'
@@ -224,8 +224,7 @@ def sig_prog(
     else:
         # TODO: why sometimes does SIGINT not work on teardown?
         # seems to happen only when trace logging enabled?
-        if not proc.poll():
+        if proc.poll() is None:
-            breakpoint()
             print(
                 f'XXX WARNING KILLING PROG WITH SIGINT XXX\n'
                 f'canc_timeout={canc_timeout!r}\n'

tractor/discovery/__init__.py

@@ -18,10 +18,11 @@
 Discovery (protocols) API for automatic addressing
 and location management of (service) actors.
 
-NOTE: to avoid circular imports, this ``__init__``
+NOTE: this ``__init__`` only eagerly imports the
-does NOT eagerly import submodules. Use direct
+``._multiaddr`` submodule (for public re-exports).
-module paths like ``tractor.discovery._addr`` or
+Heavier submodules like ``._addr`` and ``._api``
-``tractor.discovery._api`` instead.
+are NOT imported here to avoid circular imports;
+use direct module paths for those.
 
 '''
 from ._multiaddr import (

tractor/discovery/_registry.py

@@ -196,6 +196,8 @@ class Registrar(Actor):
                 and addr_tup in other_addrs
             ):
                 other_addrs.remove(addr_tup)
+                if not other_addrs:
+                    del self._registry[other_uid]
                 break
 
         # Append to this uid's addr list (avoid duplicates)

tractor/runtime/_runtime.py

@@ -1567,7 +1567,7 @@ async def async_main(
         # XXX, either passed in by caller or delivered
         # in post spawn-spec handshake for subs.
         if not accept_addrs:
-            RuntimeError(
+            raise RuntimeError(
                 f'No tpt bind addresses provided to actor!?\n'
                 f'parent_addr={parent_addr!r}\n'
                 f'accept_addrs={accept_addrs!r}\n'
@@ -1926,7 +1926,7 @@ async def async_main(
                 if failed_unreg:
                     teardown_report += (
                         f'-> Failed to unregister {actor.name} from '
-                        f'registar @ {addr}\n'
+                        f'registrar @ {addr}\n'
                     )
 
         # Ensure all peers (actors connected to us as clients) are finished