We've made a custom widget to show users on a Leaflet map. It worked fine on Mendix version 7. We recently upgraded to Mendix version 9, and now the widget behaves weird. The first time we start the project, we get an error: TypeError: L.markerClusterGroup is not a function When we rerun our app (Rerun locally button), the widget functions fine without errors. Is there a difference between starting and rerunning a project that causes this behaviour?