JavaScript errors with 'Add collection', 'Select media' (Media, Field Collection)
OK, this was sort of entertaining.

The trail begins with this silliness in media.popups.js:

dialogOptions.buttons[ok] = function () {
  alert('hell yeah');
  return "poo";


Just as it stuck out for @DeveloperWeeks, it stuck out for me because I'm familiar with the work of Media module's primary maintainer, and I know him (by reputation) to be pretty meticulous. So in checking it out I discovered that it was removed long ago (like, in 2013) in this commit: Removed inappropriate JS code. 

(I am sure he would be thrilled, by the way, to know that this bit of code will now live forever after on StackExchange. :-P)

Since the OP lists as part of his installation the latest production release  of Media (7.x-1.5), this didn't mesh. The errors were originating from a two-year-old file.

With this compelling clue in hand, @DeveloperWeeks was able to locate an extra copy of the Media module hidden away in his installation. That's when the sun rose, the flowers bloomed, and things just generally started to make more sense. 

As for those pesky errors, well...


  "This is why "duplication of data" is such a horrible thing." -
  @DeveloperWeeks


Hell, yeah. ;-)