ENH: Better errors identifiables.yaml / record type does not exist

src/caoscrawler/exceptions.py

src/caoscrawler/identifiable_adapters.py

unittests/test_crawler.py

...ta/invalid_identifiable/identifiable_content_no_list.yaml

...ata/invalid_identifiable/identifiable_no_str_or_dict.yaml

...invalid_identifiable/identifiable_referenced_no_list.yaml

unittests/test_identifiable_adapters.py

unittests/test_sync_graph.py