cosmocode/dokuwiki-plugin-publish — pull request #35 by hh-lohmann (2014-05-21 08:02:56+00:00)
Title:  Illegal string offset '_elem' in action.php on line 205

solution: put the following line at the begin of the foreach loop starting in line 204:

`if ( !isset ( $ref ['_elem'] ) ) { break ; }`

See also https://www.dokuwiki.org/plugin:publish#error_when_using_the_old_revisions_view