chore: fix typing issues (#135)

Author: aaronsteers

airbyte_cdk/sources/declarative/concurrent_declarative_source.py

@@ -206,7 +206,7 @@ def _group_streams(
             # so we need to treat them as synchronous
             if (
                 isinstance(declarative_stream, DeclarativeStream)
-                and name_to_stream_mapping[declarative_stream.name].get("retriever")["type"]
+                and name_to_stream_mapping[declarative_stream.name]["retriever"]["type"]
                 == "SimpleRetriever"
             ):
                 incremental_sync_component_definition = name_to_stream_mapping[
@@ -215,7 +215,7 @@ def _group_streams(
 
                 partition_router_component_definition = (
                     name_to_stream_mapping[declarative_stream.name]
-                    .get("retriever")
+                    .get("retriever", {})
                     .get("partition_router")
                 )
                 is_without_partition_router_or_cursor = not bool(
@@ -237,7 +237,7 @@ def _group_streams(
                     cursor = self._constructor.create_concurrent_cursor_from_datetime_based_cursor(
                         state_manager=state_manager,
                         model_type=DatetimeBasedCursorModel,
-                        component_definition=incremental_sync_component_definition,
+                        component_definition=incremental_sync_component_definition,  # type: ignore  # Not None because of the if condition above
                         stream_name=declarative_stream.name,
                         stream_namespace=declarative_stream.namespace,
                         config=config or {},
@@ -320,10 +320,11 @@ def _group_streams(
     def _is_datetime_incremental_without_partition_routing(
         self,
         declarative_stream: DeclarativeStream,
-        incremental_sync_component_definition: Mapping[str, Any],
+        incremental_sync_component_definition: Mapping[str, Any] | None,
     ) -> bool:
         return (
-            bool(incremental_sync_component_definition)
+            incremental_sync_component_definition is not None
+            and bool(incremental_sync_component_definition)
             and incremental_sync_component_definition.get("type", "")
             == DatetimeBasedCursorModel.__name__
             and self._stream_supports_concurrent_partition_processing(