Fix #395: cache is error-aware

[Tokarak]

• Use from_static instead of from_string
• On error, fallback to cache; Use hyper::Error
• Same fix for another function

Fixes: #395, but it's very difficult to replicate the conditions which triggered the bug described there.

[Tokarak]

By The Way that ugly unwrap can be fixed using .map_err for now. I decided to go all the way and try to migrate to axum 👀. That pr will have a fix for this issue, but I Can’t Be Asked to rebase Right Now.