build fails after upgrading to v7 when there are widgets that use i18n with horrible error message

[denov]

Enhancement
Package Version: 7.0.0

Code
in .dojorc "locale": "en"

Actual behavior:
running npm run dev

./node_modules/@dojo/webpack-contrib/cldr/bootstrap.js
Module not found: Error: Can't resolve 'cldr-data/main/en/ca-gregorian.json' in 'C:\......\node_modules\@dojo\webpack-contrib\cldr'
resolve 'cldr-data/main/en/ca-gregorian.json' in 'C:\......\node_modules\@dojo\webpack-contrib\cldr'
Parsed request is a module

... this goes on and on and on...

Wanted behavior:
After running the upgrade tool from v5 to v6 and then to v7 I would expect my app to build like before upgrading

I would like the upgrade script to check for the locale setting my .dojorc and install cldr-data if needed. And or the build tool to report back a better message informing me I'm missing a key package.