Fix 'failed to parse skin' bug

Author: captbaritone

packages/skin-museum-client/src/index.js

@@ -1,3 +1,14 @@
+// There is some bug between how JSZip pulls in setimmediate (which it expects
+// to polyfill `window.setimmediate` and our Webpack setup. The result is that
+// one of our bundles is missing the polyfill. If we call JSZip code from within
+// that bundle the polyfill is not present and we get an error.
+//
+// This explicit import should ensure that the polyfill is present in the
+// entrypoint bundle and thus always set on `window`.
+//
+// We should be able to remove this once we root cause the bundling issue.
+import "setimmediate";
+
 import React from "react";
 import ReactDOM from "react-dom";
 import { Provider } from "react-redux";