ReactiveCommand in current 8.0 alpha concurrency problem

[SuperJMN]

PLEASE, reproduce the issue with this solution:

WpfApp1.zip

Do you want to request a feature or report a bug?
It's a bug

What is the current behavior?
The execution of the Command throws an InvalidOperationException related to concurrency.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

Execute the attached demo (VS 2017 Preview and .NET 4.7.1, if possible, although it should fail in previous versions)

What is the expected behavior?

The Command should execute without problems.

What is the motivation / use case for changing the behavior?

Well, it's simply the way a ReactiveCommand should behave. We simply expect it to work :)

It works perfectly in the latest stable version.

Please, check the question in Stack Overflow: https://stackoverflow.com/questions/46574940/reactiveui-command-concurrency-webclient

[kentcb]

Thanks for the repro, @SuperJMN. I've found that the problem is related to the (new) separation of WPF functionality from ReactiveUI core. Without the reactiveui-wpf package, you don't have the correct initialization logic for the platform. Thus, you end up with the RxApp ambient contexts incorrectly configured, including using the wrong schedulers. Those schedulers are not using the correct thread, so things go 💥

By installing reactiveui-wpf, the problem is solved. I suspect there's something better we can do about the experience here, but I am unsure what it is just now. I'll open a separate issue to track.

[kentcb]

See #1499