Usage
Redundant import generated by rollConfig.treeshake = false
may create unusable output (for rollup it self).
npm run rollup-app-no-shake
# { a: 'a', b: undefined } not correct
npm run rollup-app
# { a: 'a', b: [ 'b', 'a' ] } correct
npm run webpack-app-no-shake
# { a: 'a', b: [ 'b', 'a' ] } correct
npm run webpack-app
# { a: 'a', b: [ 'b', 'a' ] } correct