Possible null reference argument for parameter 'source' in 'IEnumerable<string?> Enumerable.Select<SubtitleText, string?>(IEnumerable<SubtitleText> source, Func<SubtitleText, string?> selector)'.

Possible null reference return.

Dereference of a possibly null reference.

The type 'YouTubeSummariser.ApiApp.Configurations.OpenAISettings?' cannot be used as type parameter 'TService' in the generic type or method 'ServiceCollectionServiceExtensions.AddSingleton<TService>(IServiceCollection, TService)'. Nullability of type argument 'YouTubeSummariser.ApiApp.Configurations.OpenAISettings?' doesn't match 'class' constraint.

Dereference of a possibly null reference.

The type 'YouTubeSummariser.ApiApp.Configurations.PromptSettings?' cannot be used as type parameter 'TService' in the generic type or method 'ServiceCollectionServiceExtensions.AddSingleton<TService>(IServiceCollection, TService)'. Nullability of type argument 'YouTubeSummariser.ApiApp.Configurations.PromptSettings?' doesn't match 'class' constraint.

Dereference of a possibly null reference.

Possible null reference argument for parameter 'uriString' in 'Uri.Uri(string uriString)'.

Possible null reference argument for parameter 'key' in 'AzureKeyCredential.AzureKeyCredential(string key)'.