I have tried to install the extension. arc liberate will throw an error:
EXCEPTION: (XHPASTSyntaxErrorException) controller/DiagramController.php: XHPAST Parse Error: syntax error, unexpected ')' on line 919 at [<arcanist>/src/moduleutils/PhutilLibraryMapBuilder.php:461]
Reason is this unneeded comma: https://we.phorge.it/source/diagrams/browse/master/src/controller/DiagramController.php$918