diff --git a/dlt/common/utils.py b/dlt/common/utils.py
index 692f8452c9..0214bc037a 100644
--- a/dlt/common/utils.py
+++ b/dlt/common/utils.py
@@ -144,7 +144,7 @@ def flatten_list_of_str_or_dicts(seq: Sequence[Union[StrAny, str]]) -> DictStrAn
 #     return dicts
 
 
-def flatten_list_or_items(_iter: Union[Iterator[TAny], Iterator[List[TAny]]]) -> Iterator[TAny]:
+def flatten_list_or_items(_iter: Union[Iterable[TAny], Iterable[List[TAny]]]) -> Iterator[TAny]:
     for items in _iter:
         if isinstance(items, List):
             yield from items
diff --git a/dlt/helpers/streamlit_helper.py b/dlt/helpers/streamlit_helper.py
index d505ccaff3..7921e4e2e1 100644
--- a/dlt/helpers/streamlit_helper.py
+++ b/dlt/helpers/streamlit_helper.py
@@ -1,5 +1,5 @@
 import sys
-from typing import Dict, List
+from typing import Dict, List, Iterator
 import humanize
 
 from dlt.common import pendulum
@@ -253,7 +253,7 @@ def _query_data(query: str, chunk_size: int = None) -> pd.DataFrame:
         if "write_disposition" in table:
             table_hints.append("write disposition: **%s**" % table["write_disposition"])
         columns = table["columns"]
-        primary_keys = flatten_list_or_items([
+        primary_keys: Iterator[str] = flatten_list_or_items([
             col_name for col_name in columns.keys()
                 if not col_name.startswith("_") and not columns[col_name].get("primary_key") is None
         ])
diff --git a/tests/helpers/streamlit_tests/test_streamlit_show_resources.py b/tests/helpers/streamlit_tests/test_streamlit_show_resources.py
index c550b45654..fcf232ea76 100644
--- a/tests/helpers/streamlit_tests/test_streamlit_show_resources.py
+++ b/tests/helpers/streamlit_tests/test_streamlit_show_resources.py
@@ -57,10 +57,13 @@ def test_multiple_resources_pipeline():
     )
     load_info = pipeline.run([source1(10), source2(20)])
 
-    assert load_info.pipeline.schema_names == ["source2", "source1"]
-    assert load_info.pipeline.schemas.get("source1").data_tables()[0]["name"] == "one"
-    assert load_info.pipeline.schemas.get("source1").data_tables()[0]["columns"]["column_1"].get("primary_key") is True
-    assert load_info.pipeline.schemas.get("source1").data_tables()[0]["columns"]["column_1"].get("merge_key") is True
-    assert load_info.pipeline.schemas.get("source1").data_tables()[0]["write_disposition"] == "merge"
+    source1_schema = load_info.pipeline.schemas.get("source1") # type: ignore[attr-defined]
+
+    assert load_info.pipeline.schema_names == ["source2", "source1"] # type: ignore[attr-defined]
+
+    assert source1_schema.data_tables()[0]["name"] == "one"
+    assert source1_schema.data_tables()[0]["columns"]["column_1"].get("primary_key") is True
+    assert source1_schema.data_tables()[0]["columns"]["column_1"].get("merge_key") is True
+    assert source1_schema.data_tables()[0]["write_disposition"] == "merge"
 
     # The rest should be inspected using the streamlit tool.