Gatsby build error - TypeError: head.querySelector is not a function

[peterpeterparker]

Stencil version:
@stencil/core v1.12.x

I'm submitting a:
[X] bug report

Current behavior:
When I integrate Stencil Web Component in Gatsby, I face the following error at npm run build time:

(node:16791) UnhandledPromiseRejectionWarning: TypeError: head.querySelector is not a function
    at bootstrapLazy (/Users/daviddalbusco/projects/lab/gatsby-stencil/public/render-page.js:1934:42)
    at /me/project/public/render-page.js:2261:72
(node:16791) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:16791) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled

Expected behavior:
No error

Follow-up

Issue was previously reported in #2374 and solved in the ds-plugins in #39

Steps to reproduce:

• git clone https://github.com/peterpeterparker/gatsby-stencil
• cd gatsby-stencil
• npm run build