"Failed to open reporter" might mean "the collector refused my report"
In running OONI for a new test, running the new test will likely fail, perhaps because the collector doesn't allow reports for that test type.
You the user get a complaint of the form "Failed to open reporter", which doesn't at all help you understand what went wrong.
We should add whatever error checking and error passing mechanisms are needed to be able to tell the user a useful plan of action here.