Feathers: Upgrade/Generator does not work with .JS files

[TheSinding]

Steps to reproduce

• Create a non v4 project.
• Change the default.json to default.js
• Run feathers upgrade

Details

I have an existing project, which have a .js file extention on the default config.
When I run the upgrade command, I get a Cannot set property 'authentication' of undefined.
This is due to the upgrade / generator is expecting an default.json and not a default.js.

Expected behavior

I should upgrade the project.

Actual behavior

It throws an Cannot set property 'authentication' of undefined error

[daffl]

I published a fix that won't make it error. .js configuration files won't be updated automatically though.