Dereference of a possibly null reference.

Possible null reference return.

Possible null reference argument for parameter 'videoUrl' in 'string YouTubeVideo.GetVideoId(string videoUrl)'.

Dereference of a possibly null reference.

This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.

Cannot convert null literal to non-nullable reference type.

Dereference of a possibly null reference.

Possible null reference return.

Possible null reference argument for parameter 'videoUrl' in 'string YouTubeVideo.GetVideoId(string videoUrl)'.