How should a BackgroundService handle a fatal startup dependency failure, such as being unable to connect to a required message queue at launch?

If a background service absolutely cannot function without a dependency being available, StartAsync (or the very first check inside ExecuteAsync) should throw, which by default (in .NET 6+, with the appropriate BackgroundServiceExceptionBehavior configured) can bring down the entire host -- appropriate 'fail fast' behavior for critical dependencies, versus implementing a retry-with-backoff connection loop inside ExecuteAsync if brief startup unavailability should be tolerated instead of crashing the whole app.

protected override async Task ExecuteAsync(CancellationToken stoppingToken) {
    // Fail-fast option: let it throw and crash the host
    await _queueClient.ConnectAsync(stoppingToken);  // throws if unreachable

    // OR resilient option: retry with backoff instead of crashing
    await RetryConnectWithBackoffAsync(stoppingToken);
}