Returning results as dictionary leads to errors in tree.py when called in other methods

As per the documentation, we can make the return value of a tree node a dictionary for custom names:
This works, however, if we wish to import the tree node function and use it in another tree node, i.e. `results = tree_with_dict_return(...)`, it throws the following error from tree.py:
I assume this is a bug from the code handling sockets of tree functions.