handle missing field in English translation

csl.py

@@ -39,4 +39,7 @@ class Csl(datasets.GeneratorBasedBuilder):
         with gzip.open(filepath) as f:
             for key, row in enumerate(f):
                 data = json.loads(row)
+                if "category_eng" not in data:
+                    data["category_eng"] = ""
+                    data["discipline_eng"] = ""
                 yield key, data