introduce the database and controller connections for all inbounds

src/airport/airport.service.ts

@@ -25,9 +25,9 @@ export class AirportService {
   }
 
   async airport(icao: string): Promise<Airport> {
-    return this.airportModel.find({ icao }).then((response) => {
-      if (!response || response.length !== 1) return null;
-      return response[0];
+    return this.airportModel.findOne({ icao }).then((response) => {
+      if (!response) return null;
+      return response;
     });
   }