Node "Cannot find package 'X' imported from" in CI - Fix the ESM Package Resolution

This ESM error means the loader resolved a bare import specifier to a package that is not installed under node_modules on the CI runner.

What this error means

A program run as ESM throws Error: Cannot find package "<name>" imported from <file>. The package is missing or was a dev dependency pruned in CI.

node

node:internal/modules/esm/resolve:854
Error: Cannot find package 'lodash-es' imported from
/home/runner/work/app/app/src/index.js
    at packageResolve (node:internal/modules/esm/resolve:854:9) {
  code: 'ERR_MODULE_NOT_FOUND'
}

Common causes

The package is not installed in CI

A dependency is imported but missing from package.json, or was a devDependency omitted by a production install.

A bare specifier that should be a relative path

An import meant to point at a local file was written as a bare package specifier.

How to fix it

Install the package as the right dependency type

Add the package to dependencies if it is needed at runtime.
Reinstall and commit the lockfile.

Terminal

npm install lodash-es

Use a relative path for local modules

If the import targets a local file, make it a relative path with an extension.

JavaScript

import { fn } from './lib/fn.js';

How to prevent it

Keep runtime imports in dependencies (not devDependencies), commit the lockfile, and distinguish bare package specifiers from relative paths.