Project builds but fails on deploy

[charbelnicolas]

Describe the bug

Today I updated my project with an NPM Update and it no longer works correctly. This is what my package.json look like:

The project builds succesfully:

And this is what happens when it gets deployed:

Click here to see the issue for yourself

Reproduction

I could not reproduce this issue with a clean svelte-kit install. It is mostly a bug based on my project I guess... but this only happened after doing an NPM update today.

Logs

No response

System Info

System:
    OS: Linux 6.1 Arch Linux
    CPU: (8) x64 Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
    Memory: 29.83 GB / 31.30 GB
    Container: Yes
    Shell: 5.1.16 - /bin/bash
  Binaries:
    Node: 19.6.1 - /usr/bin/node
    Yarn: 1.22.19 - /usr/bin/yarn
    npm: 8.19.2 - /usr/bin/npm
  Browsers:
    Chromium: 110.0.5481.100

Severity

blocking all usage of SvelteKit

Additional Information

No response

[Conduitry]

Hm. @Rich-Harris @dummdidumm Do we need to rethink using .mjs files if they're unlikely to get the appropriate Content-Type headers served in various static servers? Or at least document the configuration changes that are needed? It looks like this particular site is using nginx.

[charbelnicolas]

Hm. @Rich-Harris @dummdidumm Do we need to rethink using .mjs files if they're unlikely to get the appropriate Content-Type headers served in various static servers? Or at least document the configuration changes that are needed? It looks like this particular site is using nginx.

Yep, I'm using Nginx :)

[Conduitry]

In the meantime, you should be able to configure nginx to return the appropriate Content-Type: application/javascript header for .mjs files.

[charbelnicolas]

In the meantime, you should be able to configure nginx to return the appropriate Content-Type: application/javascript header for .mjs files.

Thank you, I'll see what I can do.

[charbelnicolas]

I changed the mime.types file on the server and it works now, thank you!

I still get this message though:

Any idea of why that is?

[dummdidumm]

Any chance you're using Firefox? The preload optimazation doesn't work there and you instead get a warning like this

[Rich-Harris]

The screenshot looks like Chrome. I'm actually seeing the same thing on kit.svelte.dev, bizarrely:

There's definitely a bug here. Perhaps those modules really aren't being imported, though I don't understand why they'd be in the preload list otherwise

[charbelnicolas]

Any chance you're using Firefox? The preload optimazation doesn't work there and you instead get a warning like this

I'm using the latest chrome version

[tony19]

I'm also seeing this problem but with text/plain:

start.93eb02de.mjs:1 Failed to load module script: Expected a JavaScript module script but the server responded with a MIME type of "text/plain". Strict MIME type checking is enforced for module scripts per HTML spec.
app.1f02cb34.mjs:1 Failed to load module script: Expected a JavaScript module script but the server responded with a MIME type of "text/plain". Strict MIME type checking is enforced for module scripts per HTML spec.

• Chrome Version 109.0.5414.119
• macOS Ventura
• nginx

I tried the fix from #9142 in v1.8.3, but that seemed to have no effect. I had to revert to SvelteKit v1.5.0 for now.

[Conduitry]

#9142 is unrelated to this issue.

[Rich-Harris]

@tony19 is that an error you can reproduce or is it something in your logs? if the latter, it's probably because someone tried to load that file after a redeploy happened while they were on the site. it's generally harmless as the client will detect a new version and automatically reload

[tony19]

@Rich-Harris It's the former... reproducible just by visiting the site. In my case, the site completely fails to load because of that error. I just get a blank screen. I'll try to create an isolated reproduction if needed.

[Rich-Harris]

@tony19 yes please — it sounds like a separate issue though, so please open a new ticket

[rob-balfre]

This has broken our SPA builds too... we have the worst CDN on Azure and it doesn't let us serve .mjs files.

This a deliberate change to force us over to Vercel 😂 ??

[wickning1]

I also found that the precompress option fails after the switch to mjs, likely because of this glob

kit/packages/kit/src/core/adapt/builder.js

Line 85 in b3c31a1

const files = await glob('**/*.{html,js,json,css,svg,xml,wasm}', {

[polyzen]

Relevant: https://pagure.io/mailcap/pull-request/10
Mailcap strictly obeys https://www.iana.org/assignments/media-types/media-types.xhtml . I can not merge this until mjs is recognized by IANA as valid file extension.

On Arch Linux (and other distros perhaps), nginx pulls in mailcap for mime.types use by default.