Error: Cannot find module 'pug'
   at Function.Module._resolveFilename (module.js:470:15)
   at Function.Module._load (module.js:418:25)
   at Module.require (module.js:498:17)
   at require (internal/module.js:20:19)
   at new View (/srv/node_modules/express/lib/view.js:80:30)
   at Function.render (/srv/node_modules/express/lib/application.js:569:12)
   at ServerResponse.render (/srv/node_modules/express/lib/response.js:961:7)
   at app.use (/srv/src/server/server.js:69:9)
   at Layer.handle_error (/srv/node_modules/express/lib/router/layer.js:71:5)
   at trim_prefix (/srv/node_modules/express/lib/router/index.js:310:13)