Many error messages when using DruTeX

I get the following error messages when drutex is enabled. It's working OK otherwise, though. Any ideas?

Notice: Use of undefined constant filter - assumed 'filter' in preg_replace() (line 1 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex.module(363) : regexp code).
Notice: Use of undefined constant filter - assumed 'filter' in preg_replace() (line 1 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex.module(363) : regexp code).
Notice: Use of undefined constant filter - assumed 'filter' in preg_replace() (line 1 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex.module(363) : regexp code).
Notice: Use of undefined constant filter - assumed 'filter' in preg_replace() (line 1 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex.module(363) : regexp code).
Notice: Use of undefined constant filter - assumed 'filter' in preg_replace() (line 1 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex.module(363) : regexp code).
Notice: Undefined variable: id in drutex_render() (line 327 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_render.inc).
Notice: Undefined index: in _drutex_references() (line 100 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_numbering.inc).
Notice: Undefined variable: id in drutex_render() (line 327 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_render.inc).
Notice: Undefined index: in _drutex_references() (line 100 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_numbering.inc).
Notice: Undefined variable: id in drutex_render() (line 327 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_render.inc).
Notice: Undefined index: in _drutex_references() (line 100 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_numbering.inc).
Notice: Undefined variable: id in drutex_render() (line 327 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_render.inc).
Notice: Undefined index: in _drutex_references() (line 100 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_numbering.inc).
Notice: Undefined variable: id in drutex_render() (line 327 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_render.inc).
Notice: Undefined index: in _drutex_references() (line 100 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_numbering.inc).
Notice: Undefined variable: id in drutex_render() (line 327 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_render.inc).
Notice: Undefined index: in _drutex_references() (line 100 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_numbering.inc).
Notice: Undefined variable: id in drutex_render() (line 327 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_render.inc).
Notice: Undefined index: in _drutex_references() (line 100 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_numbering.inc).
Notice: Use of undefined constant filter - assumed 'filter' in preg_replace() (line 1 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex.module(363) : regexp code).
Notice: Use of undefined constant filter - assumed 'filter' in preg_replace() (line 1 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex.module(363) : regexp code).
Notice: Trying to get property of non-object in drutex_linebreak_node2html_postprocess() (line 49 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex_linebreak.inc).
Notice: Undefined index: en in drutex_node_view() (line 81 of /Volumes/Data/Projects/website/local/sites/all/modules/drutex/drutex.module).