Klipper: Avoid a crash on exit with the legacy application

Caused by the context menu and the associated widget being set to the
same object, leading to an access after destruction.

 Application: Klipper (klipper), signal: Segmentation fault
 Content of s_kcrashErrorMessage: std::unique_ptr<char []> = {get() = 0x0}
 #8 QObject::disconnect (member=0x0, ...)
 #9 KStatusNotifierItem::~KStatusNotifierItem () at knotifications/src/kstatusnotifieritem.cpp:71
 #10 KlipperTray::~KlipperTray () at plasma-workspace/klipper/tray.h:13

klipper/tray.cpp

@@ -34,6 +34,18 @@ KlipperTray::KlipperTray()
     slotSetToolTipFromHistory();
 }
 
+KlipperTray::~KlipperTray()
+{
+    // Klipper abuses the KStatusNotifierItem slightly by setting both
+    // the associated widget and the context menu to the same widget,
+    // the KlipperPopup.  This is done so that either a left click or a
+    // right click on the icon brings up the combined menu.  Unfortunately
+    // this causes a crash in ~KStatusNotifierItem() when it first
+    // deletes the menu and then tries to disconnect the associated widget.
+    // Work around this by resetting the associated widget first.
+    setAssociatedWidget(nullptr);
+}
+
 void KlipperTray::slotSetToolTipFromHistory()
 {
     const int TOOLTIP_LENGTH_LIMIT = 200;

klipper/tray.h

@@ -16,6 +16,7 @@ class KlipperTray : public KStatusNotifierItem
 
 public:
     KlipperTray();
+    ~KlipperTray() override;
 
 public Q_SLOTS:
     void slotSetToolTipFromHistory();