I think this is caused by PHPStorm. The IDE cannot understand import syntax when importing a CommonJS module.
I got this warning when using WebStorm 2016.1.2 too.
Taking react and react-router as an example:
react is a CommonJS module developed using ES5 syntax;react-router developed using ES2015 syntax and compiled by Babel.
WebStorm 2016.1.2 may allow Link exported by the react-router module, but cannot allow createClass exported by the react module.
Update
browser-sync is a CommonJS module developed with ES5. But it works well on WebStorm, WebStorm can allow all APIs exported by browser-sync .
This baffled me that WebStorm could not allow the exported react API.
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