Demo fails to work with a createReader error

[Kevnz]

The Bug
When trying the demo in Firefox/Safari/Edge after dropping an image onto the dropzone the reading images indicator appears but nothing happens. Then looking at the console shows the following error.

Unhandled Promise Rejection: TypeError: e.createReader is not a function. (In 'e.createReader()', 'e.createReader' is undefined)

To Reproduce

1. Go to http://thekevinscott.github.io/ml-classifier-ui/ in Safari/Edge/Firefox
2. Drop an image onto the dropzone
3. View the Javascript Console
4. See error

Expected behaviour
The page to work as described in the post