Docker E2E tests fail with ERR_CONNECTION_CLOSED

[textbook]

When running the E2E tests in a Docker network, which is used in CI to verify that the production application can build and run correctly in Node 8, 10 and 12, the following error occurs:

> cypress run

Fontconfig warning: "/etc/fonts/fonts.conf", line 100: unknown element "blank"

====================================================================================================

  (Run Starting)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Cypress:    3.8.1                                                                              │
  │ Browser:    Electron 78 (headless)                                                             │
  │ Specs:      1 found (home.test.js)                                                             │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘


────────────────────────────────────────────────────────────────────────────────────────────────────
                                                                                                    
  Running:  home.test.js                                                                    (1 of 1)
ERR_CONNECTION_CLOSED (-100) loading 'https://app/__/#/tests/integration/home.test.js'
Error: ERR_CONNECTION_CLOSED (-100) loading 'https://app/__/#/tests/integration/home.test.js'
    at rejectAndCleanup (electron/js2c/browser_init.js:5879:21)
    at WebContents.failListener (electron/js2c/browser_init.js:5889:11)
    at WebContents.emit (events.js:203:13)

This doesn't seem to be specific to the starter kit, raised with Cypress maintainers as cypress-io/cypress#5482