Bummer and script error 'Unexpected token <' in browser console when opening Portfolio plan page

Problem

When opening the Portfolio plan page a bummer message appears, the details are empty and look like

When opening the dev tools of the browser, in the console we can see the following script error:
Uncaught syntax error: Unexpected token <

This error happens when Portfolio's feedback issue collector that cannot properly be downloaded.

Workaround

Try to hard-refresh the Portfolio plan page (e.g., CMD+R in Chrome in OSX) or clear the browser cache.

We are working on a solution.