Fix for getting one

ref #13

src/controllers/TrackController.ts

@@ -37,7 +37,9 @@ export class TrackController {
 	@OnUndefined(TrackNotFoundError)
 	@OpenAPI({ description: "Returns a track of a specified id (if it exists)" })
 	async getOne(@Param('id') id: number) {
-		return new ResponseTrack(await this.trackRepository.findOne({ id: id }));
+		let track = await this.trackRepository.findOne({ id: id });
+		if (!track) { throw new TrackNotFoundError(); }
+		return new ResponseTrack(track);
 	}
 
 	@Post()