Guard `reg_portal` for `None` in `maybe_open_portal()`

Fix potential `AttributeError` when `query_actor()` yields
a `None` portal (peer-found-locally path) and an `OSError`
is raised during transport connect.

Also,
- fix `Arbiter.delete_addr()` return type to
  `tuple[str, str]|None` bc it can return `None`.
- fix "registar" typo -> "registrar" in comment.

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

tractor/_discovery.py

@@ -222,8 +222,9 @@ async def maybe_open_portal(
         # to) indicate that the target actor can't be
         # contacted at that addr.
         except OSError:
-            # NOTE: ensure we delete the stale entry from the
+            # NOTE: ensure we delete the stale entry
-            # registar actor.
+            # from the registrar actor when available.
+            if reg_portal is not None:
                 uid: tuple[str, str] = await reg_portal.run_from_ns(
                     'self',
                     'delete_addr',
@@ -234,6 +235,12 @@ async def maybe_open_portal(
                     f'addr: {addr!r}\n'
                     f'uid: {uid!r}\n'
                 )
+            else:
+                log.warning(
+                    f'Connection to {addr!r} failed'
+                    f' and no registry portal available'
+                    f' to delete stale entry.'
+                )
             yield None
 
 

tractor/_runtime.py

@@ -2038,7 +2038,7 @@ class Arbiter(Actor):
     async def delete_addr(
         self,
         addr: tuple[str, int|str],
-    ) -> tuple[str, str]:
+    ) -> tuple[str, str]|None:
         uid: tuple | None = self._registry.inverse.pop(
             addr,
             None,