[HttpGet]
[Route( "page" )]
public async Task<IActionResult> GetPage(
    int? page, int? size,
    CancellationToken ct)
{
    try {
        var response = await _mailService.GetPageAsync( page, size, ct: ct );
        return Respond( response ); // Turn service response into HTTP response
    }
    catch (OperationCanceledException) {
        // When reaching here, Exception already logged
        // If it should be cancelled
        if (ct.IsCancellationRequested) {
            // Empty result
            return new EmptyResult();
        }
        else {
            // Else raise again
            throw; // Never reached
        }
    }
}

try {
    page = query.ToListAsync( ct );
catch(TaskCanceledException){
    // When reaching here, Exception already logged
    return null;
}

var logConfig = new LoggerConfiguration()
    .MinimumLevel.Debug()
    .Enrich.FromLogContext();
    // Add Sinks

// Create Logger
Log.Logger = logConfig.CreateLogger();


// Configure()
loggerFactory.AddSerilog();