blockbook: make proper use of thiserror functionalities

This commit uses the `#[from]` attribute to:

- delegate the `source()` implementation of the `std::error::Error`
trait to the source error (could possibly also be done using the
`#[source]` attribute).

- generate `From` trait implementations.

Note: The `#[from]` attribute always implies that the corresponding
field is also the source, so no need to specify the `#[source]`
attribute. See:
https://docs.rs/thiserror/1.0.47/thiserror/index.html

src/lib.rs

@@ -75,26 +75,14 @@ pub mod websocket;
 pub enum Error {
     /// An error during a network request.
     #[error("error occured during the network request: {0}")]
-    RequestError(reqwest::Error),
+    RequestError(#[from] reqwest::Error),
     /// An error while parsing a URL.
     #[error("invalid url: {0}")]
-    UrlError(url::ParseError),
+    UrlError(#[from] url::ParseError),
 }
 
 type Result<T> = std::result::Result<T, Error>;
 
-impl From<reqwest::Error> for Error {
-    fn from(e: reqwest::Error) -> Self {
-        Self::RequestError(e)
-    }
-}
-
-impl From<url::ParseError> for Error {
-    fn from(e: url::ParseError) -> Self {
-        Self::UrlError(e)
-    }
-}
-
 /// A REST client that can query a Blockbook server.
 ///
 /// Provides a set methods that allow strongly typed

src/websocket.rs

@@ -71,7 +71,7 @@ pub enum Error {
     WebsocketClosed,
     /// A WebSocket error.
     #[error("the websocket connection experienced a fatal error: {0:?}\nreinstantiate the client to reconnect")]
-    Websocket(std::sync::Arc<tokio_tungstenite::tungstenite::Error>),
+    Websocket(#[from] std::sync::Arc<tokio_tungstenite::tungstenite::Error>),
 }
 
 type Result<T> = std::result::Result<T, Error>;
@@ -198,7 +198,7 @@ impl Client {
     pub async fn new(url: url::Url) -> Result<Self> {
         let stream = tokio_tungstenite::connect_async(url)
             .await
-            .map_err(|e| Error::Websocket(e.into()))?;
+            .map_err(std::sync::Arc::new)?;
         let (shutdown_tx, shutdown_rx) = tokio::sync::oneshot::channel();
         let (job_tx, job_rx) = futures::channel::mpsc::channel(10);
         tokio::spawn(Self::process(stream.0, job_rx, shutdown_rx));
@@ -282,7 +282,7 @@ impl Client {
                             response_channels
                                 .iter_mut()
                                 .map(|(_,ch)| {
-                                    ch.send(Err(Error::Websocket(err.clone())))
+                                    ch.send(Err(err.clone().into()))
                                 })
                                 .collect::<futures::stream::FuturesUnordered<_>>()
                                 .collect::<Vec<std::result::Result<_, _>>>()