If nginx.server.snippets is not defined in my pillar file, the run fails. Just adding ```{}``` as value is enough to work around the problem. The issue seems to be occuring at the pop in nginx/snippets.sls. Currently using https://github.com/saltstack-formulas/nginx-formula/commit/19203409aeb40b042cffb0e4d39bc66303f17842