Return empty list for a postcode with no historic EPC shard 🟥

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/repositories/historic_epc/test_historic_epc_s3_repository.py

@@ -13,6 +13,7 @@ from contextlib import contextmanager
 from unittest.mock import patch
 
 import pandas as pd
+from botocore.exceptions import ClientError
 
 from backend.utils.addressMatch import AddressMatch
 from datatypes.epc.domain.historic_epc import HistoricEpc
@@ -56,3 +57,20 @@ def test_get_for_postcode_maps_reader_rows_to_historic_epc_records():
     assert isinstance(records[0], HistoricEpc)
     assert records[0].address == "47 GORDON ROAD"
     assert records[0].uprn == "100"
+
+
+def test_valid_postcode_with_no_stored_object_returns_empty_list():
+    # Arrange — a valid postcode whose shard does not exist in S3.
+    def missing(bucket: str, key: str) -> pd.DataFrame:
+        raise ClientError(
+            {"Error": {"Code": "NoSuchKey", "Message": "missing"}}, "GetObject"
+        )
+
+    repo = HistoricEpcS3Repository(read_csv_gz=missing)
+
+    # Act
+    with _valid_postcode():
+        records = repo.get_for_postcode("AB33 8AL")
+
+    # Assert — a miss is the normal, expected outcome, not an exception.
+    assert records == []