SortedList indexer implementation of IDictionary throws ArgumentNullException in Desktop

[Priya91]

SortedList<TKey,TValue>, IDictionary.this[object key] throws ArgumentException when the key is not compatible with TKey

On Desktop ArgumentNullException is thrown. ArgumentNullException is incorrect, as key is not null, ArgumentException is more suited. This is a behavior change, filing issue to track on what we want to do with these differences.

cc @terrajobst @weshaggard @stephentoub @danmosemsft

[weshaggard]

This doesn't really add enough value to really warrant the change from desktop so I we should just make .NET Core behave the same as .NET Framework.

[Priya91]

.NET Core Collections need to be cleaned up to throw ArgumentNullException in the specified cases in the issue description.

[robosek]

So when key is incompatible .NET Core Collections should throw ArgumentNullException instead of ArgumentException just like it is on Desktop ?

[Priya91]

So when key is incompatible .NET Core Collections should throw ArgumentNullException instead of ArgumentException just like it is on Desktop ?

Yes, I don't think it's all of the collections, only generic SortedList IDictionary indexer implementation.

[karelz]

Fixed by above dotnet/corefx#12803