try to recover from unknown message type

src/protocol.rs

@@ -183,11 +183,16 @@ impl Message {
 
 impl fmt::Display for Message {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        let msg_type =
+            match self.message_type() {
+                Err(e) => format!("UNKNOWN {e}"),
+                Ok(t) => t.to_string(),
+            };
         write!(
             fmt,
             "client {:x} message = {} data = {} byte(s)",
             self.client_id(),
-            self.message_type().map_err(|_| fmt::Error)?,
+            msg_type,
             self.payload_len()
         )
     }

src/receive/dispatch.rs

@@ -71,7 +71,14 @@ pub(crate) fn start<F>(receiver: &receive::Receiver<F>) -> Result<(), receive::E
             continue;
         }
 
-        let message_type = message.message_type()?;
+        let message_type =
+            match message.message_type() {
+                Err(e) => {
+                    log::error!("message of UNKNOWN type received ({e}), dropping it");
+                    continue;
+                }
+                Ok(mt) => mt,
+            };
 
         let mut will_end = false;