Expose IErrorHandler and add test case.

[imcarolwang]

For issue #5561.

[mconnew]

I'm trying to understand why you added this to the ref assembly as it's internal?

[imcarolwang]

I think the request at #5561 suggests adding ClientRuntime.EnableFaults. It is internal in the src implementation

wcf/src/System.ServiceModel.Primitives/src/System/ServiceModel/Dispatcher/ClientRuntime.cs

Line 225 in 4e6e777

internal bool EnableFaults

, so I brought the same to the ref project.

Would you recommend that we update it?

[mconnew]

That was my mistake, we don't need to expose EnableFaults.

[imcarolwang]

@mconnew Thank you for letting me know. I’ve updated the PR to remove the exposure of "EnableFaults." Following your suggestion, I’ve rebased the branch and made changes only to the netcoreapp reference assembly by modifying the System.ServiceModel.Primitives.Netcoreapp.cs file. Would you mind taking another look when you have a chance to confirm if everything looks good now?

[mconnew]

Everything looks good except the question around the internal EnableFaults. With the recent changes I made to support netstandard2.0 and netfx, we have multiple ref assemblies. When you rebase, only add to the netcoreapp ref assembly, we aren't updating the netstandard2.0 reference assembly beyond what it currently is as it's only there to support those using that capability from the 4.10.x packages.