Fix crash because intermediate function result goes out of scope

Author: JulianThijssen

src/ScatterplotPlugin.cpp

@@ -133,7 +133,7 @@ ScatterplotPlugin::ScatterplotPlugin(const PluginFactory* factory) :
         if (datasetsMimeData->getDatasets().count() > 1)
             return dropRegions;
 
-        const auto& dataset         = datasetsMimeData->getDatasets().first();
+        const auto dataset          = datasetsMimeData->getDatasets().first();
         const auto datasetGuiName   = dataset->text();
         const auto datasetId        = dataset->getId();
         const auto dataType         = dataset->getDataType();