There seems to be a syntax error in the 'lib/web/fetch/util.js' file, causing a compilation error.

[woohyun1031]

Bug Description

I upgraded to undici version 6.7.0 in a specific library I'm using, and I encountered a compilation error.
While tracing the issue, I found that it originated from the file 'lib/web/fetch/util.js'.
And the file is being compiled through the SWC loader in Next.js.
Of course, it could be a different error, but I'm curious if the exception handling within the FastIterableIterator class in the createIterator function in that file is correct.

class FastIterableIterator {
    /** @type {any} */
    #target;
...
    next() {
...
        if (typeof this !== 'object' || this === null || !(#target in this)) {
          throw new TypeError(
            `'next' called on an object that does not implement the iterator interface.`
          );
        }
...
    }
...

I'm curious whether the part where the exception handling is performed on line 776 should be changed from !(#target in this) to !(this.#target in this).

Logs & Screenshots

Environment

Mac M1 Pro
Next.js 14.0.1
Node v20.10.0

[tsctx]

I think it is a swc issue.

[KhafraDev]

#prop in this is valid syntax. This is not an issue in undici.

[fersan96]

@woohyun1031 Hello, I hope you are doing well, I would like to know if you solved this problem?

[woohyun1031]

@fersan96 Hello, Unfortunately, I couldn't resolve the issue. I had to downgrade the version of undici.
but it seems like Next.js parser issue. Check this #2954. It might be helpful to you