fix: Ignore NameError when introspecting plan functions

When getting type hints to determine if a function is a plan, a
NameError can be raised (specifically when checking pydantic.Field in
this case) and the context loading crashes. Ignoring the error in the
same way that we ignore TypeError allows us to ignore broken types.

As we are only interested in specific return types (Generator) this
shouldn't affect which functions are treated as plans.

Author: tpoliaw

src/blueapi/core/bluesky_types.py

@@ -75,7 +75,7 @@ def is_bluesky_plan_generator(func: PlanGenerator) -> bool:
         return (get_origin(return_type) == Generator) and (
             get_args(return_type)[0] == Msg
         )
-    except TypeError:
+    except (TypeError, NameError):
         # get_type_hints fails on some objects (such as Union or Optional)
         return False