pandas-devGH-44312 fixes unwanted TypeError when a missing metadata field is missing

Author: qdbp

pandas/io/json/_normalize.py

@@ -389,6 +389,8 @@ def _pull_field(
         try:
             if isinstance(spec, list):
                 for field in spec:
+                    if result is None:
+                        raise KeyError()
                     result = result[field]
             else:
                 result = result[spec]