Update NST.py

NST.py

@@ -269,7 +269,7 @@ class Nst(datasets.GeneratorBasedBuilder):
                             if fields["age"].lower() in ("slethei", "ramslie") or not fields["age"].strip():
                                 fields["age"] = 0
                             for int32_field in ("number_of_recordings", "recording_session", "sheet_number", "channels", "t0", "t1", "t2"):
-                                if not fields[int32_field].strip():
+                                if isinstance(fields[int32_field], str) and not fields[int32_field].strip():
                                     fields[int32_field] = 0
                             yield metadata_key, {
                                 "id": metadata_key,