Not sure if this is the correct page for this, but over a few years I have helped a lot of users that run into problems with gadgets. It seems like a common task is to identify which gadgets breaks the chain and why it happens. This has lead me to a conclusion that it would be nice to be able to have unit tests on gadgets. It could be a button besides the gadgets on the special page and if a user pushes the button the unit tests are run. In addition there should be a button to run a unit test on all gadgets in sequence. This would solve most of the problems when something croaks cleanly, but sometimes things croaks only in certain setups. In those cases I think it would be nice to have something like the debug url parameter, but instead run the sequence of unit tests on a specific page. This will make it possible to identify interdependences betweens code that makes it croak only in some contexts.
Closelly related to this is if it would be possible to post a report from a unit test directly from the gadget page, or some other place, to Bugzilla to report a problem. Make it extremely simple to report a problem, its difficult enough for the user to identify the problem at all.