Add protocol string to Error::UnknownProtocolString (#1355)

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

misc/multiaddr/src/errors.rs

@@ -14,7 +14,7 @@ pub enum Error {
     InvalidUvar(decode::Error),
     ParsingError(Box<dyn error::Error + Send + Sync>),
     UnknownProtocolId(u32),
-    UnknownProtocolString,
+    UnknownProtocolString(String),
     #[doc(hidden)]
     __Nonexhaustive
 }
@@ -28,7 +28,7 @@ impl fmt::Display for Error {
             Error::InvalidUvar(e) => write!(f, "failed to decode unsigned varint: {}", e),
             Error::ParsingError(e) => write!(f, "failed to parse: {}", e),
             Error::UnknownProtocolId(id) => write!(f, "unknown protocol id: {}", id),
-            Error::UnknownProtocolString => f.write_str("unknown protocol string"),
+            Error::UnknownProtocolString(string) => write!(f, "unknown protocol string: {}", string),
             Error::__Nonexhaustive => f.write_str("__Nonexhaustive")
         }
     }

misc/multiaddr/src/protocol.rs

@@ -171,7 +171,7 @@ impl<'a> Protocol<'a> {
                 let s = iter.next().ok_or(Error::InvalidProtocolString)?;
                 Ok(Protocol::Memory(s.parse()?))
             }
-            _ => Err(Error::UnknownProtocolString)
+            unknown => Err(Error::UnknownProtocolString(unknown.to_string()))
         }
     }