bug fixes

verarbeitung/test_output.json

-{"nodes": [{"doi": "doi_h02", "name": "title_h02", "author": ["contributor_h02"], "year": "date_h02", "journal": "journal_h02", "group": "Input", "depth": 0, "citations": 1}, {"doi": "doi_h1", "name": "title_h1", "author": ["contributor_h1"], "year": "date_h1", "journal": "journal_h1", "group": "Citedby", "depth": 1, "citations": 1}, {"doi": "doi_h2", "name": "title_h2", "author": ["contributor_h2"], "year": "date_h2", "journal": "journal_h2", "group": "Citedby", "depth": 2, "citations": 1}], "links": [{"source": "doi_h1", "target": "doi_h02"}, {"source": "doi_h2", "target": "doi_h1"}]}
\ No newline at end of file
+{"nodes": [{"doi": "doi_h02", "name": "title_h02", "author": ["contributor_h02"], "year": "date_h02", "journal": "journal_h02", "group": "Input", "depth": 0, "citations": 1}, {"doi": "doi_h1", "name": "title_h1", "author": ["contributor_h1"], "year": "date_h1", "journal": "journal_h1", "group": "Citedby", "depth": 1, "citations": 1}, {"doi": "doi_h2", "name": "title_h2", "author": ["contributor_h2"], "year": "date_h2", "journal": "journal_h2", "group": "Citedby", "depth": 2, "citations": 1}], "links": [{"source": "doi_h1", "target": "doi_h02"}, {"source": "doi_h2", "target": "doi_h1"}]}