Are there special considerations that need to made with installing sugar when Timber is installed through Composer? Currently when installing it and trying to execute the dummy function I get an error:

Uncaught Error: Class 'Twig_Filter_Function' not found in /wp-content/plugins/sugar/timber-sugar.php

I'm loading Timber within the functions.php exactly as defined on https://timber.github.io/docs/getting-started/setup/#via-github-for-developers.

I've installed Sugar within a different instance where Timber is installed as a WordPress plugin instead and everything seems to function without any issue.