Babeljs finding files that don't exist

I am getting the following very confusing message when I run 'ember serve'

[BABEL] Note: The code generator has deoptimised the styling of "ember-blog/bower_components/moment/min/locales.js" as it exceeds the max of "100KB"

It is also throwing the following error:

SyntaxError: ember-blog/bower_components/moment/templates/locale-header.js: Unexpected token (6:0)
  4 |    factory(global.moment)
  5 | }(this, function (moment) { 'use strict';
> 6 | 

I used to have the moment package installed, but it has now been deleted. A check of the filesystem with ls -la reveals that there is no folder called 'moment', so how is Babel finding a file?

I tried deleting the files in the 'tmp' directory but that did not solve the problem.