Fix unreachable code issues, enable checking.

The loadout case actually could (and previously did) hide bugs from the
type checker, since mypy was smart enough to see that we were removing
None from the input it assumed that the member was non-optional, but
later modifications could cause null values, and since those came from
the UI mypy couldn't reason about this. This meant that mypy assumed the
type could not be optional and wouldn't check that case.

gen/flights/flightplan.py

@@ -219,11 +219,7 @@ class FlightPlan:
         tot_waypoint = self.tot_waypoint
         if tot_waypoint is None:
             return None
-
-        time = self.tot
-        if time is None:
-            return None
-        return time - self._travel_time_to_waypoint(tot_waypoint)
+        return self.tot - self._travel_time_to_waypoint(tot_waypoint)
 
     def startup_time(self) -> Optional[timedelta]:
         takeoff_time = self.takeoff_time()

gen/flights/loadouts.py

@@ -19,7 +19,11 @@ class Loadout:
         is_custom: bool = False,
     ) -> None:
         self.name = name
-        self.pylons = {k: v for k, v in pylons.items() if v is not None}
+        # We clear unused pylon entries on initialization, but UI actions can still
+        # cause a pylon to be emptied, so make the optional type explicit.
+        self.pylons: Mapping[int, Optional[Weapon]] = {
+            k: v for k, v in pylons.items() if v is not None
+        }
         self.date = date
         self.is_custom = is_custom
 

mypy.ini

@@ -13,7 +13,7 @@ namespace_packages = True
 no_implicit_optional = True
 warn_redundant_casts = True
 # warn_return_any = True
-# warn_unreachable = True
+warn_unreachable = True
 warn_unused_ignores = True
 
 [mypy-dcs.*]