The published version appears to be CommonJS only: $ node index.mjs import { isString } from 'super-utils-plus' ^^^^^^^^ SyntaxError:

The published version appears to be CommonJS only: $ node index.mjs import { isString } from 'super-utils-plus' ^^^^^^^^ SyntaxError: Named export 'isString' not found. The requested module 'super-utils-plus' is a CommonJS module, which may not support all module.exports as named exports. You might also need to update some of your type checks to handle wrapper objects like new String() - Object.prototype.toString.call(...) is your friend.