Hi
Regarding your question about React XHRs: This is currently only solvable with custom actions, as those XHRs most likely do not happen as part of an action and we therefore do not capture them (While this is just an assumption, this is the issue with a very high probability).
In RUM on Grail we will capture all XHR/fetch requests and resources (images, scripts, ...), so you will be able to see them. We will have a different approach to actions (name is still TBD) that will be a bit more forgiving when it comes to grouping requests together. It may still be necessary to use the API though, since with all the async execution of javascript in modern applications we will simply not be able to determine the purpose of all requests happening in your application)
Regarding the question about error capturing: My guess is that the error boundary is catching the exception and then handles it React-internally, which means the browser never actually fires the error event, which is where we (or any other code for that matter) would be able to capture it.
Hope that helps
Simon
