{"action":"opened","issue":{"url":"https://api.github.com/repos/babel/babel/issues/1561","labels_url":"https://api.github.com/repos/babel/babel/issues/1561/labels{/name}","comments_url":"https://api.github.com/repos/babel/babel/issues/1561/comments","events_url":"https://api.github.com/repos/babel/babel/issues/1561/events","html_url":"https://github.com/babel/babel/issues/1561","id":77549203,"number":1561,"title":"Exception in IE11","user":{"login":"Manuel-S","id":1771314,"avatar_url":"https://avatars.githubusercontent.com/u/1771314?v=3","gravatar_id":"","url":"https://api.github.com/users/Manuel-S","html_url":"https://github.com/Manuel-S","followers_url":"https://api.github.com/users/Manuel-S/followers","following_url":"https://api.github.com/users/Manuel-S/following{/other_user}","gists_url":"https://api.github.com/users/Manuel-S/gists{/gist_id}","starred_url":"https://api.github.com/users/Manuel-S/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Manuel-S/subscriptions","organizations_url":"https://api.github.com/users/Manuel-S/orgs","repos_url":"https://api.github.com/users/Manuel-S/repos","events_url":"https://api.github.com/users/Manuel-S/events{/privacy}","received_events_url":"https://api.github.com/users/Manuel-S/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-05-18T08:00:10Z","updated_at":"2015-05-18T08:00:10Z","closed_at":null,"body":"I set up a hello world example using aurelia and babel, but while it worked in chrome, I had no luck in IE. \r\nThe exception I get is \"Die Eigenschaft \"Symbol(id)_i.22alybn8ccc\" kann nicht definiert werden: Das Objekt ist nicht erweiterbar\" (The Property \"...\" cannot be defined: The object is not extendable) But it's hard to trace the source of it.\r\nAsked in the gitter if somebody knows what's going on, and @zloirock said \"it's issue with core-js Map or Set and frozen objects, but it's tested for this case and should works correct. Possible conflict with other library. I can't find problem in stack trace.\"\r\n\r\nSo without further ado, here's the minimal example:\r\n\r\nrun `npm init` with defaults, `jspm init` with defaults (babel), `jspm install aurelia-bootstrapper`\r\n\r\nfile index.html\r\n\r\n```html\r\n<!DOCTYPE html>\r\n<html>\r\n    <head>\r\n        <title>Test-App</title>\r\n    </head>\r\n    <body aurelia-app>\r\n        <script src=\"jspm_packages/system.js\"></script>\r\n        <script src=\"config.js\"></script>\r\n        <script>\r\n            System.import('aurelia-bootstrapper');\r\n        </script>\r\n    </body>\r\n</html>\r\n```\r\n\r\nfile app.html\r\n\r\n```html\r\n<template>\r\n  <section>\r\n    <h2>${heading}</h2>\r\n\r\n    <form role=\"form\" submit.delegate=\"welcome()\">\r\n      <div class=\"form-group\">\r\n        <label for=\"fn\">First Name</label>\r\n        <input type=\"text\" value.bind=\"firstName\" class=\"form-control\" id=\"fn\" placeholder=\"first name\">\r\n      </div>\r\n      <div class=\"form-group\">\r\n        <label for=\"ln\">Last Name</label>\r\n        <input type=\"text\" value.bind=\"lastName\" class=\"form-control\" id=\"ln\" placeholder=\"last name\">\r\n      </div>\r\n      <div class=\"form-group\">\r\n        <label>Full Name</label>\r\n        <p class=\"help-block\">${fullName}</p>\r\n      </div>\r\n      <button type=\"submit\" class=\"btn btn-default\">Submit</button>\r\n    </form>\r\n  </section>\r\n</template>\r\n```\r\n\r\nfile app.js\r\n\r\n```javascript\r\nexport class Welcome{\r\n  constructor(){\r\n  this.heading = 'Hello World!';\r\n  this.firstName = 'John';\r\n  this.lastName = 'Doe';\r\n  }\r\n\r\n  get fullName(){\r\n    return `${this.firstName} ${this.lastName}`;\r\n  }\r\n\r\n  welcome(){\r\n    alert(`Welcome, ${this.fullName}!`);\r\n  }\r\n}\r\n```\r\n\r\nHope someone can find what's going on here."}}