My thinking is that the majority of bootstrap tests will use the `with-app-*` macros, for which I haven't bothered doing overloads to control whether a `Throwable` is thrown for an init/start failure or the `app` instance is returned.

For the `bootstrap-*` tests, though, having the ability to parameterize this seems useful.  There are several shutdown tests cases which use the `app` instance return route and I found the need to write some additional tests that use this path when implementing the tests for the `check-for-errors!` function.  The tests I would write for the Jetty9 test case would use the same path as well.

I agree overall that these test cases should be relatively rare but would prefer not to duplicate this functionality in testutils to provide this separate path as it would seem to make the code less maintainable over time.  I can change this, though, if this is going to be too problematic.