Headless tests failing

[shoosya]

Tests with cypress-file-upload run absolutely fine in Google Chrome, but fail in headless mode with the following error:

Oops...we found an error preparing this test file:

  /Users/shoosya/src/support/index.js

The error was:

Error: Cannot find module 'cypress-file-upload' from '/Users/shoosya/src/cypress/support'

This occurred while Cypress was compiling and bundling your test code. This is usually caused by:

- A missing file or dependency
- A syntax error in the file or one of its dependencies

Fix the error in your code and re-run your tests.

I followed all the installation instructions.
Why might this be happening?

The command I use to run headless tests is:
$ docker run -it -v $PWD:/Users/shoosya/src/ -w /Users/shoosya/src/ cypress/included:3.2.0

/Users/shoosya/src/ is the path to my project.