when running the route the node sends me this message: Error: Can not set headers after they are sent

When accessing the route you specify, the files that I have in the public folder are not loaded, only some are loaded and in the nodejs console you send me the following message:

Error: Can't set headers after they are sent.
    at SendStream.headersAlreadySent (C:\api-rest\node_modules\send\index.js:402:13)
    at SendStream.send (C:\api-rest\node_modules\send\index.js:625:10)
    at onstat (C:\api-rest\node_modules\send\index.js:737:10)
    at FSReqWrap.oncomplete (fs.js:123:15)
Error: Can't set headers after they are sent.
    at SendStream.headersAlreadySent (C:\api-rest\node_modules\send\index.js:402:13)

My code is as follows:

app.get('/', (req, res, err) => {

Noticias.find({}, (e, noticias) => {
    noticias.forEach(function (element) {
        var myStrin = '' + element.Contenido;
        myStrin = myStrin.slice(0, 100);
        element.Contenido = myStrin + '...';
    }, this);
    if (e) {
        console.log(e);
    } else if (!noticias) {
        console.log("Error, el archivo no existe")
    } else {
        res.render('index', { noticias, title: "ICMA", uno: "select", dos: "", tres: "", cuatro: "", cinco: "" })
    }
   }) 
});