merge bitcoin-core/gui#673: Use fallback value for Version and User Agent during peer connection

Author: kwvg

src/qt/rpcconsole.cpp

@@ -1304,8 +1304,12 @@ void RPCConsole::updateDetailWidget()
     ui->peerPingTime->setText(GUIUtil::formatPingTime(stats->nodeStats.m_last_ping_time));
     ui->peerMinPing->setText(GUIUtil::formatPingTime(stats->nodeStats.m_min_ping_time));
     ui->timeoffset->setText(GUIUtil::formatTimeOffset(stats->nodeStats.nTimeOffset));
-    ui->peerVersion->setText(QString::number(stats->nodeStats.nVersion));
-    ui->peerSubversion->setText(QString::fromStdString(stats->nodeStats.cleanSubVer));
+    if (stats->nodeStats.nVersion) {
+        ui->peerVersion->setText(QString::number(stats->nodeStats.nVersion));
+    }
+    if (!stats->nodeStats.cleanSubVer.empty()) {
+        ui->peerSubversion->setText(QString::fromStdString(stats->nodeStats.cleanSubVer));
+    }
     ui->peerConnectionType->setText(GUIUtil::ConnectionTypeToQString(stats->nodeStats.m_conn_type, /* prepend_direction */ true));
     ui->peerTransportType->setText(QString::fromStdString(TransportTypeAsString(stats->nodeStats.m_transport_type)));
     if (stats->nodeStats.m_transport_type == TransportProtocolType::V2) {