node_modules/core-js/modules/_collection-to-json.js

// https://github.com/DavidBruant/Map-Set.prototype.toJSON
var classof = require('./_classof');
var from = require('./_array-from-iterable');
module.exports = function (NAME) {
  return function toJSON() {
    if (classof(this) != NAME) throw TypeError(NAME + "#toJSON isn't generic");
    return from(this);
  };
};