Fix crash when loading gcode file twice (#7217)

* Fix ASAN use-after-free error when loading 3mf file with gcode by drag-and-drop

* Fix crash when loading gcode file twice

src/slic3r/GUI/Plater.cpp

@@ -10128,6 +10128,10 @@ void Plater::load_gcode(const wxString& filename)
         set_project_filename(filename);
     }
 
+    // Orca: Fix crash when loading gcode file multiple times
+    if (m_only_gcode) {
+        p->view3D->get_canvas3d()->remove_raycasters_for_picking(SceneRaycaster::EType::Bed);
+    }
 }
 
 void Plater::reload_gcode_from_disk()
@@ -12347,15 +12351,13 @@ void Plater::reslice()
         // Post the "complete" callback message, so that it will slice the next plate soon
         wxQueueEvent(this, evt.Clone());
         p->m_is_slicing = true;
-        this->SetDropTarget(nullptr);
         if (p->m_cur_slice_plate == 0)
             reset_gcode_toolpaths();
         return;
     }
 
     if (result) {
         p->m_is_slicing = true;
-        this->SetDropTarget(nullptr);
     }
 
     bool clean_gcode_toolpaths = true;