BUG: closes pandas-dev#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]

pandas/tests/io/json/test_normalize.py

@@ -634,6 +634,23 @@ def test_missing_meta(self, missing_metadata):
         expected = DataFrame(ex_data, columns=columns)
         tm.assert_frame_equal(result, expected)
 
+    def test_missing_nested_meta(self):
+        # GH44312
+        # If errors="ignore" and metadata is null, we should it even if it's nested
+        data = {"meta": "foo", "nested_meta": None, "value": [{"rec": 1}, {"rec": 2}]}
+        result = json_normalize(
+            data,
+            record_path="value",
+            meta=["meta", ["nested_meta", "leaf"]],
+            errors="ignore",
+        )
+        ex_data = [["foo", np.nan, 1], ["foo", np.nan, 2]]
+        columns = ["meta", "nested_meta.leaf", "rec"]
+        expected = DataFrame(ex_data, columns=columns).astype(
+            {"nested_meta.leaf": object}
+        )
+        tm.assert_frame_equal(result, expected, check_like=True)
+
     def test_missing_meta_multilevel_record_path_errors_raise(self, missing_metadata):
         # GH41876
         # Ensure errors='raise' works as intended even when a record_path of length