Questionable test/cast pair in OrleansJsonSerializer.cs

[Jens-G]

There is a questionable test/cast pair in OrleansJsonSerializer.cs:

• First we test against AddressableType.IsAssignableFrom(objectType) in line 289;
• the we do a hard cast in line 295: var val = (GrainReference)value;

If the instance is Addressable but not a GrainReference, you get an NPE next.

Would it maybe more correct to test sth along of objectType is GrainReference?

[ReubenBond]

Well spotted. It should be cast to IAddressable and converted to GrainReference using the non-generic AsReference extension method:

orleans/src/Orleans.Core.Abstractions/Core/GrainExtensions.cs

Line 20 in 2195a32

internal static GrainReference AsReference(this IAddressable grain)

Would you be willing to open a PR?