SampleView: prevent GUI crash if the no Python script is selected or the script is empty

GUI/View/View/SampleView.cpp

@@ -143,8 +143,11 @@ void SampleView::setToolbarActions(QToolBar* toolbar)
     import_sample_action->setToolTip(
         "Import sample from a Python script that contains a function that returns a multi-layer");
     toolbar->addAction(import_sample_action);
-    connect(import_sample_action, &QAction::triggered,
-            [this] { m_set->add_item(IO::Py::importMultiLayer()); });
+    connect(import_sample_action, &QAction::triggered, [this] {
+        SampleItem* sample_item = IO::Py::importMultiLayer();
+        if (sample_item)
+            m_set->add_item(sample_item);
+    });
 #endif
 
     auto* choose_from_library_action = new QAction("Examples", this);