fix: using _comm_default shadows possible bugs

[maartenbreddels]

This came up when working on ipython/traitlets#777, instead of _comm_default, this method seems to trigger more code paths, which revealed that we couldn't create the DataWidget (since the default was None because we didn't pass in args=()).

[jasongrout]

Thanks!

[maartenbreddels]

@meeseeksdev please backport to master

[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 master
git pull

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

git cherry-pick -x -m1 892166dd0524e93b912d8826a6da26c09afd4366

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

git commit -am 'Backport PR #3590: fix: using _comm_default shadows possible bugs'

4. Push to a named branch:

git push YOURFORK master:auto-backport-of-pr-3590-on-master

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

"Backport PR #3590 on branch master (fix: using _comm_default shadows possible bugs)"

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.