fix bug with creating json-ld with url datatypes, re #9190

[apeters]

re #9190

[jacobtylerwalls]

Fix looks good at this layer, but in retesting the bug report I found a failure later on in the same workflow, which I figure we should also address:

Request Method: GET
Request URL: http://127.0.0.1:8029/resources/139342ee-f035-44c1-8c6a-821ecb26977d

Django Version: 4.2.10
Python Version: 3.11.6

  File "/web_root/arches/arches/app/views/api.py", line 511, in get
    output = exporter.writer.write_resources(resourceinstanceids=[resourceid], indent=indent, user=request.user)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/web_root/arches/arches/app/utils/data_management/resources/formats/rdffile.py", line 275, in write_resources
    js = self.build_json(graph_id, resourceinstanceids, **kwargs)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/web_root/arches/arches/app/utils/data_management/resources/formats/rdffile.py", line 238, in build_json
    g = self.get_rdf_graph()
        ^^^^^^^^^^^^^^^^^^^^
  File "/web_root/arches/arches/app/utils/data_management/resources/formats/rdffile.py", line 211, in get_rdf_graph
    add_edge_to_graph(g, domainnode, rangenode, edge, tile, graph_info)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/web_root/arches/arches/app/utils/data_management/resources/formats/rdffile.py", line 166, in add_edge_to_graph
    graph.add((pkg["d_uri"], RDF.type, URIRef(edge.domainnode.ontologyclass)))
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/web_root/ENV/lib/python3.11/site-packages/rdflib/term.py", line 223, in __new__
    if not _is_valid_uri(value):
           ^^^^^^^^^^^^^^^^^^^^
  File "/web_root/ENV/lib/python3.11/site-packages/rdflib/term.py", line 76, in _is_valid_uri
    if c in uri: return False
       ^^^^^^^^

Exception Type: TypeError at /resources/139342ee-f035-44c1-8c6a-821ecb26977d
Exception Value: argument of type 'NoneType' is not iterable

[apeters]

Hmm, that's interesting. I did not experience that issue. I was able to create a card with 2 url nodes, populate only one of them and successfully return a json-ld doc. @jacobtylerwalls maybe we should compare setups, test models, etc...?

[jacobtylerwalls]

Looked into this further, and this was a red-herring error from not having an ontology on my graph. We can consider raising a more informative error for that separately.