And I see no Harm on making this extreme wierd usecase less user-friendly and force you to go through panic recover rather than force everyone else that will never get errors to handle errors.
It's not "extreme weird", just significantly less common, so just weird, but nowhere extreme. Dynamic routing isn't exactly unheard of, and isn't some sort of perversion - servers like Traefik and Caddy do this (except that they don't use stdlib mux, of course). Basically any DIY proxy with dynamic service discovery may need it, and while people typically pick off-the-shelf solution, some write their own lightweight one.
And panic/recover is not idiomatic Go here, as it's not an exceptional situation, just an error.
do they though? first both of them and afaik all other routers need to reload so for all intents and purposes the routing table is static, you can not add routing rules during the runtime. (Their apparent "dynamism" comes because they sighup or reload the process to put the new rules in place).
Secondly and most importantly they don't error.
Caddy will simply match the last declared rule while Traeffic has a system of priority labels and yet for conflicting rules with same priority again it will match the last one (or even worse a random one).
Both of these are very dangerous because you may realise late (from statistic logs) that you are routing the wrong requests to the wrong handler, and have already missed countless calls that should have gone on the first declared one.
