Node.js: how to do routing correctly?

Question

JavaScript

I need to use many locations on one server. I'm trying to organize this via app.use. But in the process, the engine starts to swear. How to specify it correctly?
applications folder:
--- application that routes
--- chat
--- other applications
Errors:

Error: No default engine was specified and no extension was provided.
at new View (C:\chat2\chat2\node_modules\express\lib\view.js:62:11)
at Function.render (C:\chat2\chat2\node_modules\express\lib\application.js:570:12 )
at ServerResponse.render (C:\chat2\chat2\node_modules\express\lib\response.js:971:7)
at C:\chat2\chat2\chat\index.js:41:9
at Layer.handle [as handle_request] (C:\chat2\chat2\node_modules\express\lib\router\layer.js:95:5)
at next (C:\chat2\chat2\node_modules\express\lib\router\route.js:137: 13)
at Route.dispatch (C:\chat2\chat2\node_modules\express\lib\router\route.js:112:3)
at Layer.handle [as handle_request] (C:\chat2\chat2\node_modules\express\ lib\router\layer.js:95:5)
at C:\chat2\chat2\node_modules\express\lib\router\index.js:281:22
at Function.process_params (C:\chat2\chat2\node_modules\express\lib\router\index.js:335:12 )

Git.
Help to make routing correctly.

Answer 1

It was necessary to pass io and take it to a level above engine.

module.exports = function(io, db) {
...
return router;
}

Answer 2

break nginx applications