MW 1.39.8. I am getting this error and blank page when I try to use the extension (tried php 7.4 and 8.1).
Fatal error: Declaration of MobileFormatter::parseItemsToRemove() must be compatible with HtmlFormatter\HtmlFormatter::parseItemsToRemove(): array in MobileFrontend/includes/MobileFormatter.php on line 67
Using
wfLoadExtension( 'MobileFrontend' ); wfLoadSkin( 'MinervaNeue' ); $wgDefaultMobileSkin = 'minerva';
Edit: Looks like it is an issue with HTML formatter versions. If I use in vendor/wikimedia/html-formatter
HTML formatter 3.0.1, MobileFrontend works BUT TextExtracts/Popups DO NOT work
Conversely with HTML formatter 4.0.3, TextExtracts/Popups work but not MobileFrontend.