fix: xmpp matcher not reporting potential ErrConsumedAllPrefetchedByt…

…es errors

modules/l4xmpp/matcher.go

@@ -42,7 +42,7 @@ func (m MatchXMPP) Match(cx *layer4.Connection) (bool, error) {
 	p := make([]byte, minXmppLength)
 	n, err := io.ReadFull(cx, p)
 	if err != nil || n < minXmppLength { // needs at least 50 (fix for adium/pidgin)
-		return false, nil
+		return false, err
 	}
 	return strings.Contains(string(p), xmppWord), nil
 }