added some diagnostic errors when story initialization is done withou…

…t proper driver startup first

tale/base.py

@@ -275,6 +275,10 @@ def __init__(self, name: str, title: str = None, *, descr: str = None, short_des
         self.story_data = {}  # type: Dict[Any, Any]   # not used by Tale itself, story can put custom data here. Use builtin types only.
         self.init()
         if util.get_periodicals(self):
+            if mud_context.driver is None:
+                raise TaleError("Attempt to create MudObject while Driver hasn't been properly initialized yet. "
+                                "Possible cause is importing zone or npc module files that create these objects "
+                                "early before the driver itself loads them.")
             mud_context.driver.register_periodicals(self)
 
     def init(self) -> None:

tale/driver.py

@@ -719,6 +719,10 @@ def defer(self, due: DeferDueType, action: Callable, *vargs: Any, **kwargs: Any)
         Triggering a deferred can not occur sooner than the server tick period!
         """
         assert callable(action)
+        if self.game_clock is None:
+            raise errors.TaleError("Attempt to register a deferred action while Driver hasn't been properly started yet. "
+                                   "A possible cause is importing zone or npc module files that create MudObjects "
+                                   "that use @call_periodically, before the driver has been fully started and loads these by itself.")
         if isinstance(due, datetime.datetime):
             assert due >= self.game_clock.clock
             deferred = Deferred(due, action, vargs, kwargs)