refactor: improve fmt::Debug for legacy::Error (#99)

Author: seanmonstar

src/client/legacy/client.rs

@@ -52,7 +52,6 @@ struct Config {
 }
 
 /// Client errors
-#[derive(Debug)]
 pub struct Error {
     kind: ErrorKind,
     source: Option<Box<dyn StdError + Send + Sync>>,
@@ -1566,6 +1565,17 @@ impl fmt::Debug for Builder {
 
 // ==== impl Error ====
 
+impl fmt::Debug for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut f = f.debug_tuple("hyper_util::client::legacy::Error");
+        f.field(&self.kind);
+        if let Some(ref cause) = self.cause {
+            f.field(cause);
+        }
+        f.finish()
+    }
+}
+
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "client error ({:?})", self.kind)