Call Workspace::clientHidden when ShellClient gets destroyed

Ensures that active_client gets changed if it was a ShellClient.

shell_client.cpp

@@ -61,6 +61,7 @@ ShellClient::~ShellClient() = default;
 
 void ShellClient::destroyClient()
 {
+    m_closing = true;
     Deleted *del = Deleted::create(this);
     emit windowClosed(this, del);
     waylandServer()->removeClient(this);
@@ -235,7 +236,7 @@ bool ShellClient::isResizable() const
 bool ShellClient::isShown(bool shaded_is_shown) const
 {
     Q_UNUSED(shaded_is_shown)
-    return true;
+    return !m_closing;
 }
 
 void ShellClient::maximize(MaximizeMode)

shell_client.h

@@ -98,6 +98,7 @@ private:
 
     KWayland::Server::ShellSurfaceInterface *m_shellSurface;
     QSize m_clientSize;
+    bool m_closing = false;
 };
 
 }

workspace.cpp

@@ -388,6 +388,7 @@ void Workspace::init()
         );
         connect(w, &WaylandServer::shellClientRemoved, this,
             [this] (ShellClient *c) {
+                clientHidden(c);
                 emit clientRemoved(c);
                 x_stacking_dirty = true;
                 updateStackingOrder(true);