Express Server 404ing All Requests Made From Index

In the following express/gulpfile.js code, I am having an issue with express serving the index.html fine but the index itself cannot hit the lib/* directory and just 404s all the requests made at the top of my index.html.

I am proxying browser-sync with nodemon. However I'm pretty sure it has nothing to do with my browser-sync config because when I just use node config/server.js the same problem persists.

Express config:

var express = require('express');var path = require('path');var filePaths = require('./filePaths');var app = express();//filePaths.releaseIndex === './release/index.html'app.get('/', function (req, res) {    res.sendFile(filePaths.releaseIndex, {root: './'});});app.listen(5000);

Gulp task config:

//filePaths.release === './release'//filePaths.server === './config/server.js'gulp.task('browser-sync', ['nodemon'], function() {    browserSync.init(null, {        proxy: "http://localhost:5000",        files: [filePaths.release],        browser: "google chrome",        port: 7000    });});gulp.task('nodemon', function (cb) {    var started = false;    return nodemon({        script: filePaths.server    }).on('start', function () {        if (!started) {            cb();            started = true;         }     });});

index.html:

<script src="lib/es6-shim.min.js"></script>

Folder structure:

config    server.jsrelease    index.html        lib            es6-shim.min.js            Rx.js            ...

I've tried many different variations in the res.sendFile() but just can't get a foothold although I am sure that it is the problem.

Any ideas?