Assign editor->map to nullptr after clearing map cache

include/mainwindow.h

@@ -128,6 +128,7 @@ private slots:
     void onWildMonDataChanged();
     void openNewMapPopupWindow(int, QVariant);
     void onNewMapCreated();
+    void onMapCacheCleared();
 
     void on_action_NewMap_triggered();
     void on_actionNew_Tileset_triggered();

include/project.h

@@ -219,6 +219,7 @@ private:
 signals:
     void reloadProject();
     void uncheckMonitorFilesAction();
+    void mapCacheCleared();
 };
 
 #endif // PROJECT_H