fix: delete index before initializing

tests/unit/test_layer.py

@@ -239,6 +239,8 @@ class TestRouteLayer:
 
     def test_add_route(self, routes, openai_encoder, index_cls):
         index = init_index(index_cls, sync="local")
+        # clear the index
+        index.delete_all()
         route_layer = RouteLayer(encoder=openai_encoder, index=index)
 
         # Initially, the local routes list should be empty