Webpack process only picks up some of the css files in a theme

[handrews]

As filed by @Relequestual as cloudflare/doca#40

When creating a theme with multiple css files in the styles folder, not all of them are always pick up and included.

Noted at cloudflare/doca#39 (comment)

I think I found the cause of this problem!
I had installed bootstrap, but removed the font files.
The CSS loader had a problem when it couldn't find the fonts, and died, without saying a word.
I only noticed this when I restarted the server in development mode and saw it in the console while it was trying to reload modules.
Added the fonts back, no problem.

I still came across a load order issue, but because they are loaded in alphabetical order (it seems), that's easy to fix.

Added another CSS file. Still have the problem where it's not picked up at...
require.context('doca-bootstrap-theme/styles', true, /\.css$/gi);
main.js