I think you're assuming that the panic happens when a request is received, but it actually happens when a conflicting route is registered.

To me, that's reasonable behavior and is consistent with other things such as https://pkg.go.dev/regexp#MustCompile

I think you are vastly oversimplifying what has been said or why it works the way that it does. I really recommend you read the design document and reasoning, as it is rather clear why they are doing it the way that they are. If you have a cogent contribution to the discussion, please do share.

Registering handlers is a startup activity ... Practically the only time I allow a panic in my code. I also have unit tests for the entire startup sequence so theoretically code with ambiguous handlers would never be committed.