Ah, the problem is that PluginExportHtml::copy_static_files() duplicates the logic from Theme->_get_path() (in lib/web.php), but we didn't update it both places.
Ah, the problem is that PluginExportHtm l::copy_ static_ files() duplicates the logic from Theme->_get_path() (in lib/web.php), but we didn't update it both places.