/// <summary>
/// Add a movie to an existing watchlist
/// </summary>
public async Task <ActionResult <Watchlist> > AddMovie(int watchlistId, int movieId)
{
var watchlist = await _watchlistService.AddMovieToListAsync(GetUserId(), watchlistId, movieId);
if (watchlist == null)
{
return(new BadRequestObjectResult(Errors.AddErrorToModelState("Watchlist doesn't exist", ModelState)));
}
return(new OkObjectResult(watchlist));
}