Dropping a JSON file on to the viewer does not seem to work.
Uncaught TypeError: Cannot read property '0' of null
at Function.com_watabou_toytown2_elements3d_buildings_GableRoof.add (ToyTown2.js:28511)
at com_watabou_toytown2_elements3d_View.reset (ToyTown2.js:27988)
at com_watabou_toytown2_scenes_TownScene.load (ToyTown2.js:28828)
at FileReader.reader.onload (ToyTown2.js:27408)
I missed that message of yours. "The devicemotion events are blocked..." shouldn't be a problem, it's just a warning and it doesn't prevent the rest of the code from working.
I've uploaded a small update, which at least helps with Tazshelby2016's file. In that case it was invalid geometry in JSON.