This happens only on development mode locally, not on oppia.org.
This happens with both explorations as well as collections.

• steps to reproduce the problem
  1. complete any exploration.
  2. open console.
  3. give it a rating, a feedback form should pop up.
  4. click on close, it gives console errors and doesn't close.
• observed behaviour
  1. feedback form doesn't close.
  2. gives console errors when clicked on close button.
• the expected behaviour
  should close and should not show any console errors.
• which operating system and/or browser you're using, if relevant
  Ubuntu 17.04, chrome 62.0