Disable scuttlebot site if it exists

src/freedombone-app-scuttlebot

     firewall_remove ${SCUTTLEBOT_PORT}
     firewall_remove ${GIT_SSB_PORT}
 
-    nginx_dissite ${SCUTTLEBOT_DOMAIN_NAME}
-    rm /etc/nginx/sites-available/${SCUTTLEBOT_DOMAIN_NAME}
+    if [ $SCUTTLEBOT_DOMAIN_NAME ]; then
+        nginx_dissite ${SCUTTLEBOT_DOMAIN_NAME}
+        rm /etc/nginx/sites-available/${SCUTTLEBOT_DOMAIN_NAME}
+    fi
 
     systemctl stop scuttlebot
     systemctl disable scuttlebot