examples: Add chat example that also doesn't work properly yet

examples/chat/error.go

@@ -0,0 +1,11 @@
+package chat
+
+import "fmt"
+
+func (msg *MessageError) Error() string {
+	if description, ok := msg.Description.Get(); ok {
+		return fmt.Sprintf("other party sent error: %d %s", msg.Error, description)
+	} else {
+		return fmt.Sprintf("other party sent error: %d", msg.Code)
+	}
+}