If you are using AWS Lambda Layers and using WebStorm as the IDE, probably your Layer's aren't being evaluated by the IDE due to incorrect paths. See below for a hack solution.

webstorm_lambda_layer_path_resolve.js

// Let's assume the "util.js" layer file is saved here: /lib/helpers/nodejs/util.js
// You will refer to the layer like below (according to AWS docs).
const Util = require('/opt/nodejs/src/util');

// Above will work, however WebStorm will give you annoying the "unresolved" warning
// and will not show the code completion. As a solution, create a symlink in your project
// to simulate the layer mount path. See below:
// ln -s lib/helpers opt

// MAJOR DOWNSIDE: This will only work for a single layer.
// If you have a solution for multiple layers (hack solution like above or a proper IDE level),
// please comment below.