Fix control flow.

Airlock/Airlock.cs

@@ -185,7 +185,8 @@ namespace IngameScript
             if (!airVent.CanPressurize)
             {
                 error("Airlock is not airtight.");
-                yield return false;
+                Cycling = false;
+                yield break;
             }
 
             pressurizeDepressurize();
@@ -214,6 +215,7 @@ namespace IngameScript
 
             setLights(AirlockLightState.Off);
             _console.Print("Cycling Complete.");
+            Cycling = false;
         }
 
         private void closeDoors()