widget: Add outline to nodes with no type

[andrewedstrom]

Description

Nodes without types need to be styled differently since they have no label:

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Checklist

• [ ] I have tested these changes locally and they work as expected.
• [ ] I have added or updated tests to cover any new functionality or bug fixes.
• [ ] I have updated the documentation to reflect any changes or additions to the project.
• [ ] I have followed the project's code of conduct and conventions for commit messages.

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