Error message from duplicate routes could be more helpful

[Legioth]

It's easy to end up with multiple routes with the same path by mistake, especially when playing around with the platform and copypasting examples from docs, so this is a fairly common scenario. The problem is that the resulting stack trace does not make it easy to understand what the problem is.

Could the framework print a clear and unambiguous error in the output when this is encountered, instead of relying on a cryptic stacktrace?