"unknown_conforms_to" error while running pizza01-toppings example in https://linkml.io/linkml-owl/tutorial/pizza01/

[samsontu]

After copying the pizza01-toppings-model.yaml and pizza01-toppings-data.yaml files from https://linkml.io/linkml-owl/tutorial/pizza01/, running

linkml-data2owl -s pizza01-toppings-model.yaml pizza01-toppings-data.yaml -o pizza01-toppings.ofn
Result in:
ERROR:root:Did not find unknown_conforms_to in PizzaTopping slots = []
Traceback (most recent call last):
File "/Users/tu/opt/anaconda3/bin/linkml-data2owl", line 8, in
sys.exit(cli())
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/click/core.py", line 1157, in call
return self.main(*args, **kwargs)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/click/core.py", line 1078, in main
rv = self.invoke(ctx)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/click/core.py", line 1434, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/click/core.py", line 783, in invoke
return __callback(*args, **kwargs)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/linkml_owl/dumpers/owl_dumper.py", line 822, in cli
doc = dumper.dumps(element, schemaview=sv, output_type=output_type)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/linkml_owl/dumpers/owl_dumper.py", line 185, in dumps
doc = self.to_ontology_document(element, schema, iri=iri)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/linkml_owl/dumpers/owl_dumper.py", line 165, in to_ontology_document
self.transform(e1, schema)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/linkml_owl/dumpers/owl_dumper.py", line 254, in transform
raise ValueError(f'Lookup slot in {c.name} failed for {k} // element={element}')
ValueError: Lookup slot in PizzaTopping failed for unknown_conforms_to // element=PizzaTopping(id='pizza:FishTopping', label='fish topping', conforms_to='PizzaTopping', subClassOf='pizza:PizzaTopping')

Taking out the conforms-to statements in pizza01-toppings-data.yaml and running

linkml-data2owl -C PizzaTopping -s pizza01-toppings-model.yaml pizza01-toppings-data-woconforms.yaml -o pizza01-toppings.ofn
Result in:
ERROR:root:Did not find unknown_conforms_to in PizzaTopping slots = []
Traceback (most recent call last):
File "/Users/tu/opt/anaconda3/bin/linkml-data2owl", line 8, in
sys.exit(cli())
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/click/core.py", line 1157, in call
return self.main(*args, **kwargs)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/click/core.py", line 1078, in main
rv = self.invoke(ctx)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/click/core.py", line 1434, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/click/core.py", line 783, in invoke
return __callback(*args, **kwargs)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/linkml_owl/dumpers/owl_dumper.py", line 822, in cli
doc = dumper.dumps(element, schemaview=sv, output_type=output_type)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/linkml_owl/dumpers/owl_dumper.py", line 185, in dumps
doc = self.to_ontology_document(element, schema, iri=iri)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/linkml_owl/dumpers/owl_dumper.py", line 165, in to_ontology_document
self.transform(e1, schema)
File "/Users/tu/opt/anaconda3/lib/python3.9/site-packages/linkml_owl/dumpers/owl_dumper.py", line 254, in transform
raise ValueError(f'Lookup slot in {c.name} failed for {k} // element={element}')
ValueError: Lookup slot in PizzaTopping failed for unknown_conforms_to // element=PizzaTopping(id='pizza:FishTopping', label='fish topping', conforms_to='PizzaTopping', subClassOf='pizza:PizzaTopping')