Drill 23: Beginner mistake — Async and error handling

public async Task<Course?> LoadAsync(string slug, CancellationToken token)
{
    try
    {
        return await db.Courses
            .FirstOrDefaultAsync(course => course.Slug == slug, token);
    }
    catch (OperationCanceledException)
    {
        return null;
    }
}

var course = await LoadAsync("html", CancellationToken.None);