remove check for non-leaf node

[EpigeneMax]

fixes #4774 and #3589

Code PR

• [x] I have read through the contributing notes and understand the structure of the package. In particular, if my PR modifies code of plotly.graph_objects, my modifications concern the codegen files and not generated files.
• [x] I have added tests (if submitting a new feature or correcting a bug) or modified existing tests.
• [ ] For a new feature, I have added documentation examples in an existing or new tutorial notebook (please see the doc checklist as well).
• [x] I have added a CHANGELOG entry if fixing/changing/adding anything substantial.
• [ ] For a new feature or a change in behaviour, I have updated the relevant docstrings in the code to describe the feature or behaviour (please see the doc checklist as well).