This way there is now only one way to create a router:
```rust
use axum::{Router, handler::get};
let app = Router::new()
.route("/foo", get(handler))
.route("/foo", get(handler));
```
`nest` was changed in the same way:
```rust
use axum::Router;
let app = Router::new().nest("/foo", service);
```
Previously, on `main`, this wouldn't compile:
```rust
let app = route("/", get(handler))
.layer(
ServiceBuilder::new()
.timeout(Duration::from_secs(10))
.into_inner(),
)
.handle_error(...)
.route(...); // <-- doesn't work
```
That is because `handle_error` would be
`axum::service::ServiceExt::handle_error` which returns `HandleError<_,
_, _, HandleErrorFromService>` which does _not_ implement `RoutingDsl`.
So you couldn't call `route`. This was caused by
https://github.com/tokio-rs/axum/pull/120.
Basically `handle_error` when called on a `RoutingDsl`, the resulting
service should also implement `RoutingDsl`, but if called on another
random service it should _not_ implement `RoutingDsl`.
I don't think thats possible by having `handle_error` on `ServiceExt`
which is implemented for any service, since all axum routers are also
services by design.
This resolves the issue by removing `ServiceExt` and moving its methods
to `RoutingDsl`. Then we have more tight control over what has a
`handle_error` method.
`service::OnMethod` now also has a `handle_error` so you can still
handle errors from random services, by doing
`service::any(svc).handle_error(...)`.
David Pedersen