fix: error for object dtype on read_pandas

bigframes/session/__init__.py

@@ -1050,7 +1050,12 @@ def _read_pandas(
         inline_df = self._read_pandas_inline(pandas_dataframe)
         if inline_df is not None:
             return inline_df
-        return self._read_pandas_load_job(pandas_dataframe, api_name)
+        try:
+            return self._read_pandas_load_job(pandas_dataframe, api_name)
+        except pa.ArrowInvalid as e:
+            raise pa.ArrowInvalid(
+                f"Could not convert with a BigQuery type: `{e}`. "
+            ) from e
 
     def _read_pandas_inline(
         self, pandas_dataframe: pandas.DataFrame
@@ -1064,6 +1069,10 @@ def _read_pandas_inline(
             inline_df = dataframe.DataFrame(
                 blocks.Block.from_local(pandas_dataframe, self)
             )
+        except pa.ArrowInvalid as e:
+            raise pa.ArrowInvalid(
+                f"Could not convert with a BigQuery type: `{e}`. "
+            ) from e
         except ValueError:  # Thrown by ibis for some unhandled types
             return None
         except pa.ArrowTypeError:  # Thrown by arrow for types without mapping (geo).

tests/system/small/test_session.py

@@ -24,6 +24,7 @@
 import google.cloud.bigquery as bigquery
 import numpy as np
 import pandas as pd
+import pyarrow as pa
 import pytest
 
 import bigframes
@@ -436,6 +437,11 @@ def test_read_pandas_index(session):
     pd.testing.assert_index_equal(bf_idx.to_pandas(), pd_idx)
 
 
+def test_read_pandas_w_unsupported_mixed_dtype(session):
+    with pytest.raises(pa.ArrowInvalid, match="Could not convert"):
+        session.read_pandas(pd.DataFrame({"a": [1, "hello"]}))
+
+
 def test_read_pandas_inline_respects_location():
     options = bigframes.BigQueryOptions(location="europe-west1")
     session = bigframes.Session(options)