Icon Applet: Disable plasmoid if it is defunct

Otherwise clicking it would show an "invalid URL" error and
trying to open the properties dialog would trigger an assert.

This can normally not happen but you can get here with e.g. plasmoidviewer

BUG: 455433

applets/icon/iconapplet.cpp

@@ -265,7 +265,7 @@ void IconApplet::populateFromDesktopFile(const QString &path)
     m_openWithActions.clear();
     m_jumpListActions.clear();
 
-    m_localPath = path;
+    setLocalPath(path);
 
     setBusy(false);
 }
@@ -311,6 +311,11 @@ QString IconApplet::genericName() const
     return m_genericName;
 }
 
+bool IconApplet::isValid() const
+{
+    return !m_localPath.isEmpty();
+}
+
 QList<QAction *> IconApplet::contextualActions()
 {
     QList<QAction *> actions;
@@ -569,8 +574,12 @@ QString IconApplet::localPath() const
 
 void IconApplet::setLocalPath(const QString &localPath)
 {
+    const bool oldValid = isValid();
     m_localPath = localPath;
     config().writeEntry(QStringLiteral("localPath"), localPath);
+    if (oldValid != isValid()) {
+        Q_EMIT isValidChanged();
+    }
 }
 
 K_PLUGIN_CLASS(IconApplet)

applets/icon/iconapplet.h

@@ -30,6 +30,7 @@ class IconApplet : public Plasma::Applet
     Q_PROPERTY(QString name READ name NOTIFY nameChanged)
     Q_PROPERTY(QString iconName READ iconName NOTIFY iconNameChanged)
     Q_PROPERTY(QString genericName READ genericName NOTIFY genericNameChanged)
+    Q_PROPERTY(bool valid READ isValid NOTIFY isValidChanged)
 
 public:
     explicit IconApplet(QObject *parent, const KPluginMetaData &data, const QVariantList &args);
@@ -44,6 +45,7 @@ public:
     QString name() const;
     QString iconName() const;
     QString genericName() const;
+    bool isValid() const;
 
     QList<QAction *> contextualActions() override;
 
@@ -59,6 +61,7 @@ Q_SIGNALS:
     void nameChanged(const QString &name);
     void iconNameChanged(const QString &iconName);
     void genericNameChanged(const QString &genericName);
+    void isValidChanged();
     void jumpListActionsChanged(const QVariantList &jumpListActions);
 
 private:

applets/icon/package/contents/ui/main.qml

@@ -50,6 +50,7 @@ MouseArea {
     Layout.maximumHeight: inPanel ? PlasmaCore.Units.iconSizeHints.panel : -1
 
     hoverEnabled: true
+    enabled: Plasmoid.nativeInterface.valid
 
     onClicked: Plasmoid.nativeInterface.run()
 
@@ -66,10 +67,9 @@ MouseArea {
 
     function updateActions() {
         Plasmoid.clearActions()
-
         Plasmoid.removeAction("configure");
 
-        if (Plasmoid.immutability !== PlasmaCore.Types.SystemImmutable) {
+        if (Plasmoid.nativeInterface.valid && Plasmoid.immutability !== PlasmaCore.Types.SystemImmutable) {
             Plasmoid.setAction("configure", i18n("Properties"), "document-properties");
         }
     }
@@ -85,6 +85,13 @@ MouseArea {
         }
     }
 
+    Connections {
+        target: Plasmoid.nativeInterface
+        function onValidChanged() {
+            updateActions();
+        }
+    }
+
     DragDrop.DropArea {
         id: dropArea
         anchors.fill: parent