add defined check in streams config

nginx/streams.sls

@@ -8,8 +8,10 @@
 
 {#- _nginx is a lightened copy of nginx map intended to passed in templates #}
 {%- set _nginx = nginx.copy() %}
-{%- do _nginx.pop('streams') %}
-{%- do _nginx.pop('servers') %}
+
+{%- do _nginx.pop('streams') if nginx.snippets is defined %}
+{%- do _nginx.pop('servers') if nginx.servers is defined %}
+
 
 nginx_streams_dir:
   file.directory: