don't need to do this if the user never had a CalendarProgress to begin with, probably

src/controllers/api/inventoryController.ts

@@ -109,7 +109,9 @@ export const inventoryController: RequestHandler = async (request, response) =>
             }
         }
 
-        getCalendarProgress(inventory); // handle year rollover; the client expects to receive an inventory with an up-to-date CalendarProgress
+        if (inventory.CalendarProgress) {
+            getCalendarProgress(inventory); // handle year rollover; the client expects to receive an inventory with an up-to-date CalendarProgress
+        }
 
         cleanupInventory(inventory);