If OPACPopupAuthorsSearch is enabled, clicking an author on the OPAC detail page triggers a modal dialog where the user can choose which authors should be included in the search. Clicking the submit button in this window triggers a JS error and the search is not performed.
Can't replicate (but I'm quite new to Koha). Please add some more detailed replication steps.
*** This bug has been marked as a duplicate of bug 13271 ***