Jarom,
I customized my scales and it fixes the problem. It is not a solution for our company because we need to be able to zoom in at at least 1:141 but if you don't need to zoom in closer than 1;1128 maybe try customizing your scales in WAB. So basically what happens is even though ESRI's basemap cache has all those larger scales available, there are no tiles at those scales for your area. Only certain cities actually have tiles at those scales. So instead of showing a message on the map when you zoom in to larger scales saying "map data not yet available", the web app crashes.
I tried ESRI's Imagery, Streets and Topographic and they crash. The only one that works for us is the Light Gray Canvas.
Maria