Media wysiwyg insert assumes all <a> tags link to images

Problem/Motivation

My custom module implement theme_registry_alter to override the theme_file_link function in order to remove the icon and span wrapper around a file link. The introduces an error in wysiwyg-filter.js line 146:
TypeError: element[0] is undefined

This error is introduced by the assumption in the previous lines that <a> are only wrapped around images:

      // Parse out link wrappers. They will be re-applied when the image is
      // rendered on the front-end.
      if (element.is('a')) {
        element = element.children();
      }

Proposed resolution

Add a sanity check to the assumption every <a> links to an image.

Remaining tasks

1. Write a patch
2. Review

User interface changes

None

API changes

None

Data model changes

None