The changes in rB70151e41dc02 broke subtree expansion in the Data API display mode because the closed subtrees are empty lists. Move the empty subtree check from `outliner_item_openclose` to the walk navigation code to prevent the issue.
The changes in rB70151e41dc02 broke subtree expansion in the Data API display mode because the closed subtrees are empty lists. Move the empty subtree check from `outliner_item_openclose` to the walk navigation code to prevent the issue.