diff --git a/tractor/_actor.py b/tractor/_actor.py
index fe1f67f..d46471d 100644
--- a/tractor/_actor.py
+++ b/tractor/_actor.py
@@ -168,7 +168,7 @@ class Actor:
     def __init__(
         self,
         name: str,
-        rpc_module_paths: List[str] = {},
+        rpc_module_paths: List[str] = [],
         statespace: Optional[Dict[str, Any]] = None,
         uid: str = None,
         loglevel: str = None,
diff --git a/tractor/_spawn.py b/tractor/_spawn.py
index 5e99723..a26cb8e 100644
--- a/tractor/_spawn.py
+++ b/tractor/_spawn.py
@@ -107,8 +107,8 @@ async def exhaust_portal(
 async def cancel_on_completion(
     portal: Portal,
     actor: Actor,
-    errors: List[Exception],
-    task_status=trio.TASK_STATUS_IGNORED,
+    errors: Dict[Tuple[str, str], Exception],
+    task_status: TaskStatus[trio.CancelScope] = trio.TASK_STATUS_IGNORED,
 ) -> None:
     """Cancel actor gracefully once it's "main" portal's
     result arrives.
@@ -127,29 +127,26 @@ async def cancel_on_completion(
                 f"Cancelling {portal.channel.uid} after error {result}"
             )
         else:
-            log.info(f"Cancelling {portal.channel.uid} gracefully")
+            log.info(
+                f"Cancelling {portal.channel.uid} gracefully "
+                "after result {result}")
 
         # cancel the process now that we have a final result
         await portal.cancel_actor()
 
-    # XXX: lol, this will never get run without a shield above..
-    # if cs.cancelled_caught:
-    #     log.warning(
-    #         "Result waiter was cancelled, process may have died")
-
 
 async def new_proc(
     name: str,
-    actor_nursery: 'ActorNursery',
+    actor_nursery: 'ActorNursery',  # type: ignore
     subactor: Actor,
-    errors: Dict[str, Exception],
+    errors: Dict[Tuple[str, str], Exception],
     # passed through to actor main
     bind_addr: Tuple[str, int],
     parent_addr: Tuple[str, int],
     begin_wait_phase: trio.Event,
     use_trip: bool = True,
     task_status: TaskStatus[Portal] = trio.TASK_STATUS_IGNORED
-) -> mp.Process:
+) -> None:
     """Create a new ``multiprocessing.Process`` using the
     spawn method as configured using ``try_set_start_method()``.
     """
@@ -217,7 +214,7 @@ async def new_proc(
             else:
                 fs_info = (None, None, None, None, None)
 
-            proc = _ctx.Process(
+            proc = _ctx.Process(  # type: ignore
                 target=subactor._mp_main,
                 args=(
                     bind_addr,
diff --git a/tractor/_trionics.py b/tractor/_trionics.py
index 4f97b5e..a20f8bb 100644
--- a/tractor/_trionics.py
+++ b/tractor/_trionics.py
@@ -26,7 +26,7 @@ class ActorNursery:
         actor: Actor,
         ria_nursery: trio.Nursery,
         da_nursery: trio.Nursery,
-        errors: Dict[str, Exception],
+        errors: Dict[Tuple[str, str], Exception],
     ) -> None:
         # self.supervisor = supervisor  # TODO
         self._actor: Actor = actor
@@ -57,7 +57,7 @@ class ActorNursery:
         subactor = Actor(
             name,
             # modules allowed to invoked funcs from
-            rpc_module_paths=rpc_module_paths,
+            rpc_module_paths=rpc_module_paths or [],
             statespace=statespace,  # global proc state vars
             loglevel=loglevel,
             arbiter_addr=current_actor()._arb_addr,
@@ -68,7 +68,9 @@ class ActorNursery:
         # start a task to spawn a process
         # blocks until process has been started and a portal setup
         nursery = nursery or self._da_nursery
-        return await nursery.start(
+
+        # XXX: the type ignore is actually due to a `mypy` bug
+        return await nursery.start(  # type: ignore
             _spawn.new_proc,
             name,
             self,
@@ -186,8 +188,8 @@ async def open_nursery() -> typing.AsyncGenerator[ActorNursery, None]:
 
     # XXX we use these nurseries because TRIP is doing all its stuff with
     # an `@asynccontextmanager` which has an internal nursery *and* the
-    # task that opens a nursery must also close it.
-    errors: Dict[str, Exception] = {}
+    # task that opens a nursery **must also close it**.
+    errors: Dict[Tuple[str, str], Exception] = {}
     async with trio.open_nursery() as da_nursery:
         try:
             async with trio.open_nursery() as ria_nursery:
@@ -241,7 +243,7 @@ async def open_nursery() -> typing.AsyncGenerator[ActorNursery, None]:
                     with trio.CancelScope(shield=True):
                         await anursery.cancel()
                 if len(errors) > 1:
-                    raise trio.MultiError(errors.values())
+                    raise trio.MultiError(tuple(errors.values()))
                 else:
                     raise list(errors.values())[0]
     log.debug(f"Nursery teardown complete")