Async functionality should propagate the errors/exceptions to the caller

[MaticPogacnik]

Recently the asyncGet was added, which works as expected.
But the exceptions (e.g. Timeout) are just logged and not propagated to the user.

I see two possibilities how this could be added (there are probably more):

• Add a separate callback, which is called on the error.
• Add extra arguments to the existing callback, which provide the status information.

@sveseli

[anjohnson]

Hi Matic, FYI Sinisa is now "out of the office" until mid-September, so you might not get a response until he gets back (although it wouldn't surprise me if he checks his email occasionally).

[echandler-anl]

FYI we found a separate issue related to async: async get/put block if they can't connect to the PV. Connection needs to happen on the async thread.

[sveseli]

@MaticPogacnik fixes have been incorporated into the code as of release 4.0.1.