Issue with runtimeConfig + layers in production when certain conditions are met

[Maiquu]

Environment

• Operating System: Linux
• Node Version: v20.9.0
• Nuxt Version: 3.8.1
• CLI Version: 3.9.1
• Nitro Version: 2.7.2
• Package Manager: pnpm@8.9.2
• Builder: -
• User Config: devtools, extends, runtimeConfig
• Runtime Modules: -
• Build Modules: -

Reproduction

Reproduction repository: https://github.com/Maiquu/nuxt-bug-reproduction

Since this is a build-only issue, I haven't included a StackBlitz link. I included notes in README about the issue.

Describe the bug

If all of the following conditions are met, the build output will not read environment variable equivalents of runtime configuration keys that were undefined at build time.

• Main app should extend a layer which is defined as a node module.
• Extended layer should have runtimeConfig defined with any number of values.

Build output will not be flawed if extended layer is defined as a relative path. (EDIT: This is incorrect, layer type does not matter)

Can be worked around by giving a default value for any runtimeConfig expression that can be undefined during build.

Logs

No response

[v-moravec]

Why was this closed? I don't see any PR that would fix the issue. It seems I'm getting the same bug.

[Maiquu]

I'm not really sure why I closed it back then. Maybe I thought it was a very rare and minor issue with a simple workaround, making it not worth the time. But yes, after checking again, there is still inconsistent behavior in how undefined initial values are handled for runtimeConfig. I can re-open the issue with the reproduction repo if you think its necessary.

[v-moravec]

I already created my own minimal reproduction, might dig into it later.