Address pr feedback paritytech#1

types/src/client.rs

@@ -138,9 +138,8 @@ impl<Notif> Drop for Subscription<Notif> {
 impl<Notif> Drop for NotificationHandler<Notif> {
 	fn drop(&mut self) {
 		// We can't actually guarantee that this goes through. If the background task is busy, then
-		// the channel's buffer will be full, and our unsubscription request will never make it.
-		// However, when a notification arrives, the background task will realize that the channel
-		// to the `Subscription` has been closed, and will perform the unsubscribe.
-		let _ = self.to_back.send(FrontToBack::UnregisterNotification((&self.method).to_owned())).now_or_never();
+		// the channel's buffer will be full, and our unregister request will never make it.
+		let notif_method = std::mem::take(&mut self.method);
+		let _ = self.to_back.send(FrontToBack::UnregisterNotification(notif_method)).now_or_never();
 	}
 }

ws-client/src/client.rs

@@ -595,18 +595,16 @@ async fn background_task(
 				let (subscribe_tx, subscribe_rx) = mpsc::channel(max_notifs_per_subscription);
 
 				if manager.insert_notification_handler(&reg.method, subscribe_tx).is_ok() {
-					reg.send_back
-						.send(Ok((subscribe_rx, reg.method)))
-						.expect("error sending response for notification handler");
+					let _ = reg.send_back.send(Ok((subscribe_rx, reg.method)));
 				} else {
 					let _ = reg.send_back.send(Err(Error::MethodAlreadyRegistered(reg.method)));
 				}
 			}
 
-			// User called `on_notification` on the front-end.
+			// User dopped the notificationHandler for this method
 			Either::Left((Some(FrontToBack::UnregisterNotification(method)), _)) => {
 				log::trace!("[backend] unregistering notification handler: {:?}", method);
-				let _ = manager.remove_notification_handler(&method);
+				let _ = manager.remove_notification_handler(method);
 			}
 			Either::Right((Some(Ok(raw)), _)) => {
 				// Single response to a request.

ws-client/src/manager.rs

@@ -159,8 +159,8 @@ impl RequestManager {
 	}
 
 	/// Removes a notification handler
-	pub fn remove_notification_handler(&mut self, method: &str) -> Result<(), Error> {
-		if let Some(_) = self.notification_handlers.remove(&method.to_owned()) {
+	pub fn remove_notification_handler(&mut self, method: String) -> Result<(), Error> {
+		if let Some(_) = self.notification_handlers.remove(&method) {
 			Ok(())
 		} else {
 			Err(Error::UnregisteredNotification(method.to_owned()))