edit: add description of related route-matching issue

Describe the bug

1. In examples/hackernews_islands_axum, the category function is called twice, leading to incorrect article listings for "new" and "job" (both end up with the "news" catch-all).

2. Additionally, if the path doesn't get matched by the router and does not exist as a fallback static file, the server panics.

Leptos Dependencies

Reproduces from tag 0.8.0-rc3 with example https://github.com/leptos-rs/leptos/tree/main/examples/hackernews_islands_axum

To Reproduce

git clone https://github.com/leptos-rs/leptos.git
cd leptos/examples/hackernews_islands_axum
cargo leptos watch

1. Visit http://localhost:8080/ and http://localhost:8080/jobs in the browser and notice they're the same.
2. Visit http://localhost:8080/explode/panic or http://localhost:8080/stories/ and see no data returned and a server panic

Next Steps

[X] I will make a PR
[ ] I would like to make a PR, but need help getting started
[ ] I want someone else to take the time to fix this
[ ] This is a low priority for me and is just shared for your information

Additional context
Add any other context about the problem here.