Deleting a project in a non-windows environment gives warnings and errors because it cannot delete the testscript directories. The problem lies in this line in project_controller.php:
$array_items = array_merge($array_items, $this->directoryToArray($directory. "
" . $file, $recursive));
It uses a windows-only directory seperator (backslash, ) instead of the directory seperator (DS) constant. Because the directories aren't deleted, the next time a project is created with the same name it throws errors too (because the directories already exist).
Fix: resplace "
" with DS:
$array_items = array_merge($array_items, $this->directoryToArray($directory. DS . $file, $recursive));