From f397f072df1ed7476dc7cf907775d93575e42625 Mon Sep 17 00:00:00 2001
From: Ismael Asensio <isma.af@gmail.com>
Date: Mon, 26 Oct 2020 23:27:54 +0100
Subject: [PATCH] Reply a meaningful dBus error when detecting unmanaged
 windows

Currently, the method `createErrorReply()` with empty strings
errors out and the client gets no answer:
```
QDBusConnection: error: could not send error message to service "":
Error name cannot be empty
```

Simple test:
qdbus org.kde.KWin /KWin org.kde.KWin.showDebugConsole
qdbus org.kde.KWin /KWin org.kde.KWin.queryWindowInfo

Error name uses D-Bus Interface-like notation as suggested in
https://doc.qt.io/qt-5/qdbuserror.html#name

CCBUG: 340477
---
 dbusinterface.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dbusinterface.cpp b/dbusinterface.cpp
index 3f8ae2e3f5..df681d75a6 100644
--- a/dbusinterface.cpp
+++ b/dbusinterface.cpp
@@ -219,7 +219,9 @@ QVariantMap DBusInterface::queryWindowInfo()
             if (auto c = qobject_cast<AbstractClient*>(t)) {
                 QDBusConnection::sessionBus().send(m_replyQueryWindowInfo.createReply(clientToVariantMap(c)));
             } else {
-                QDBusConnection::sessionBus().send(m_replyQueryWindowInfo.createErrorReply(QString(), QString()));
+                QDBusConnection::sessionBus().send(m_replyQueryWindowInfo.createErrorReply(
+                    QStringLiteral("org.kde.KWin.Error.InvalidWindow"),
+                    QStringLiteral("Tried to query information about an unmanaged window")));
             }
         }
     );