While testing with Firefox browser v54.0.1, in the meteor demo on line 39 of client/main.js 🔗 the saveAs call is causing an error, because it seems to be undefined.

If I add to file package.json dependencies:
"file-saver": "1.3.3"

and add somewhere near to the top of the file main.js:
const FILESAVER = require('file-saver');

then change at line 39 of main.js
from: saveAs(
to: FILESAVER.saveAs(...

The errors go away and the file save as dialog appears as expected.