Failed to fetch dynamically imported module

Describe the bug

Hi, we are using SvelteKit on production for a while now and recently added Sentry to monitor errors.

Some of our settings:

• SSR: off
• Pre-render: disabled
• adapter: static
• hosting: netlify
• it’s a SPA (we have fallback to index.html)

The error log looks something like this: Failed to fetch dynamically imported module: https://<our_page.com>/_app/pages/index.svelte-91a57275.js

And the odd thing is that it does not happen on any particular route and not always, but often enough.

Reproduction

It is not reproducible on development and it happens randomly. Probably something to do with SPA?

Logs

TypeError: 'text/html' is not a valid JavaScript MIME type.
Failed to fetch dynamically imported module: https://<our_page.com>/_app/pages/index.svelte-91a57275.js

System Info

System:
    OS: macOS 12.0.1
    CPU: (8) x64 Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
    Memory: 31.21 MB / 8.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 14.17.2 - ~/.nvm/versions/node/v14.17.2/bin/node
    Yarn: 1.22.17 - /usr/local/bin/yarn
    npm: 7.23.0 - ~/.nvm/versions/node/v14.17.2/bin/npm
    Watchman: 2022.01.03.00 - /usr/local/bin/watchman
  Browsers:
    Brave Browser: 98.1.35.101
    Chrome: 98.0.4758.102
    Firefox: 97.0
    Safari: 15.1
  npmPackages:
    @sveltejs/adapter-static: ^1.0.0-next.28 => 1.0.0-next.28
    @sveltejs/kit: ^1.0.0-next.266 => 1.0.0-next.266
    svelte: ^3.45.0 => 3.45.0

Severity

serious, but I can work around it

Additional Information

No response

[goynang]

To follow up on how I solved my problem, in case it helps…

I removed…

[functions]
    node_bundler = "esbuild"

…which I had added a while back to resolve some other problem building on Netlify. With that gone everything builds fine for me again now (including with latest version of kit). Until next time I guess.

[el-schneider]

I’m also suddenly getting very similar errors and while my build is not failing the deployed website isn’t working.

Edit: everything is working fine locally. Going back to previously deployed (and working) commits is however not working anymore. I’m using the netlify-adapter btw. Looks to me like maybe netlify has changed something.