```rust
error[E0277]: `syn::attr::NestedMeta` doesn't implement `std::fmt::Debug`
--> src/route.rs:149:57
|
149 | attr => panic!("Unknown attribute{:?}", attr),
| ^^^^ `syn::attr::NestedMeta` cannot be formatted using `{:?}` because it doesn't implement `std::fmt::Debug`
|
= help: the trait `std::fmt::Debug` is not implemented for `syn::attr::NestedMeta`
= note: required because of the requirements on the impl of `std::fmt::Debug` for `&syn::attr::NestedMeta`
= note: required by `std::fmt::Debug::fmt`
```