Resolve core_path before calling nodejs

[fcollonval]

References

Fixes #13125

Code changes

Resolve core_path before calling nodejs subprocess

User-facing changes

Consistent resolution of relative path to cwd for jupyter labextension build

Backwards-incompatible changes

No

[jupyterlab-probot]

Thanks for making a pull request to jupyterlab!
To try out this branch on binder, follow this link:

[fcollonval]

@meeseeksdev please backport to 3.4.x

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 3.4.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 040d7fec4114c3737ec454b3bedeed6b01af370e

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #13126: Resolve core_path before calling nodejs'

4. Push to a named branch:

git push YOURFORK 3.4.x:auto-backport-of-pr-13126-on-3.4.x

5. Create a PR against branch 3.4.x, I would have named this PR:

"Backport PR #13126 on branch 3.4.x (Resolve core_path before calling nodejs)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.