Rollup only knows about your code by default, it has no idea about node_modules code or how to resolve it. As such
we must configure it to know how to resolve node modules you might import.
This will now allow Rollup to import the native ES6 module magic-string (that just happens to be a a dependency of
rollup-plugin-commonjs) with a default and a named import of Bundle, and the Commonjs module arr-diff which
uses the module.exports syntax for both a default export. The commonjs plugin also also supports custom named
exports from CJS npm modules if the default export is a plain old javascrit object (POJO), see the
CommonJs plugin docs for details.
Go ahead and run this with yarn serve and check the console, you should get: