Submit your issue here: https://github.com/zordius/lightncandy/issues/new
Proper sample input data with template is prefered. If you can provide the LightnCandy version (or commit hash) and some sample code of your setup/helpers it will be better.
Pull request is another good way. Before you submit your patch, please ensure you run full tests:
git submodule init
git submodule update
composer install
build/runphp build/gen_test.php
build/test