🐛 BUG: Uncaught TypeError: Class extends value undefined is not a constructor or null

[Skye-31]

Which Cloudflare product(s) does this pertain to?

Wrangler core, Other

What version(s) of the tool(s) are you using?

Wrangler 3.5.0

What version of Node are you using?

18.17.0

What operating system are you using?

Mac

Describe the Bug

When creating a worker that defines a Durable Object (but doesn't export it in the main file), a very cryptic error is thrown

service core:user:my-worker: Uncaught TypeError: Class extends value undefined is not a constructor or null
  at index.js:1648:44 in maskDurableObjectDefinition
  at index.js:1657:26
✘ [ERROR] MiniflareCoreError [ERR_RUNTIME_FAILURE]: The Workers runtime failed to start. There is likely additional logging output above.

We should probably check whether the main script exports the DO, and if it doesn't, provide an easier to understand error.

Please provide a link to a minimal reproduction

export default {}
// note, the lack of `export class MyDO`

name = "my-worker"
script = "src/index.ts"
compatibility_date = "2023-08-11"

[[durable_objects.bindings]]
name = "MY_DO"
class_name = "MyDO"

[[migrations]]
tag = "v1"
new_classes = ["MyDo"]

Please provide any relevant error logs

No response

[Meai]

@Skye-31 I am also getting this error in a nextjs project after doing a next-on-pages build but I am already exporting the class

[Skye-31]

I am also getting this error in a nextjs project after doing a next-on-pages build but I am already exporting the class

@Meai that sounds like a different issue - this is purely for improving the messaging when you're not exporting the DO. As a side note, I don't believe pages supports Durable Objects within Functions - you'd have to bind to a separate worker

[gerhardcit]

I am also getting this error in a nextjs project after doing a next-on-pages build but I am already exporting the class

@Meai that sounds like a different issue - this is purely for improving the messaging when you're not exporting the DO. As a side note, I don't believe pages supports Durable Objects within Functions - you'd have to bind to a separate worker

Have this changed recently @Skye-31 . I think pages do support Durable Objects now. It would be great to see a good example of how to export a DO class correctly?