The "m" field in the extended handshake is not mandatory

connection.go

@@ -892,11 +892,7 @@ func (c *connection) mainReadLoop() error {
 				if v, ok := d["v"]; ok {
 					c.PeerClientName = v.(string)
 				}
-				m, ok := d["m"]
-				if !ok {
-					err = errors.New("handshake missing m item")
-					break
-				}
+				if m, ok := d["m"]; ok {
 					mTyped, ok := m.(map[string]interface{})
 					if !ok {
 						err = errors.New("handshake m value is not dict")
@@ -920,6 +916,7 @@ func (c *connection) mainReadLoop() error {
 							c.PeerExtensionIDs[name] = byte(id)
 						}
 					}
+				}
 				metadata_sizeUntyped, ok := d["metadata_size"]
 				if ok {
 					metadata_size, ok := metadata_sizeUntyped.(int64)