GithubClient.Repository.GetAllLanguages throws Exception when the repo does not have a language

[baonguyen96]

Example with this API endpoint: https://api.github.com/users/vinhhoa1/repos
Using the above code will crash with this error for repository RPG-ZombiesTCC:

System.ArgumentNullException: Value cannot be null.

Parameter name: source

   at System.Linq.Enumerable.Select[TSource,TResult](IEnumerable`1 source, Func`2 selector)

   at Octokit.RepositoriesClient.<GetAllLanguages>d__84.MoveNext()

I think it would be better if null value are marked as "" (empty) rather than throwing an exception here.

[ryangribble]

Hi @baonguyen96

Can you provide the c# code that produced the error?

The API link you provided (getting all repos for a user) doesn't correlate to the the stack trace. RepositoriesClient.GetAllLanguages() would correspond to https://api.github.com/repos/vinhhoa1/RPG-ZombiesTCC/languages

We definitely dont want an exception like this occurring, but I just want to get the repro code in this issue for completeness 👍

[baonguyen96]

@ryangribble Sure here is the link to the source code: https://github.com/baonguyen96/GitData/blob/dev/GitData/Storage/Repository.cs

Particularly, it breaks on line 41 (language = await ....) when I call the API to retrieve all languages and any of the language is null:

IReadOnlyList<Octokit.RepositoryLanguage> languages = null;
Task.Run(async () =>
{
                languages = await githubClient.Repository.GetAllLanguages(octokitRepository.Owner.Login, Name);
}).GetAwaiter().GetResult();

This exception does not happen when a repository has at least 1 language.

[ryangribble]

@baonguyen96 can you please take a look at #1831 and let me know if that would suit your needs? Do you have a preference between returning an empty list or returning a null? I went with empty list

[baonguyen96]

@ryangribble yes I definitely prefer the empty list to null. Thank you.