style(lib): address clippy code style warnings

* Remove unnecessary return statements.

* Combine identical `match` arms.

* Collapse nested conditional.

* Use `assert_ne` where applicable.

* Lifetime elision.

src/server/mod.rs

@@ -426,7 +426,7 @@ impl<S, B> Server<S, B>
         let wait = WaitUntilZero { info: info.clone() };
         match core.run(wait.select(timeout)) {
             Ok(_) => Ok(()),
-            Err((e, _)) => return Err(e.into())
+            Err((e, _)) => Err(e.into())
         }
     }
 }