I've been working with the bare minimum data I need to make the app work, and today I just added all the layers that will be in the app, mainly additional landbase data.
I've decided to not use an Esri basemap since we have so many areas with no coverage. So, I removed the basemap property from the Map object.
However, when I go to generate the data, it fails. If I put the basemap property back, then the data generates fine.
How can I generate the data without defining a basemap? The first layer I add to the map is our service area boundary, so I thought that'd work.