diff --git a/gen3discoveryai/main.py b/gen3discoveryai/main.py
index af064aa1..a839b1d8 100644
--- a/gen3discoveryai/main.py
+++ b/gen3discoveryai/main.py
@@ -1,7 +1,7 @@
 import os
+import traceback
 from contextlib import asynccontextmanager
 from importlib.metadata import version
-import traceback
 
 import fastapi
 import yaml
@@ -105,19 +105,14 @@ async def lifespan(fastapi_app: fastapi.FastAPI):
             }
             config.topics[topic].update(topic_raw_cfg["metadata"])
 
-            chain_instance = chain_factory.get(
-                topic_raw_cfg["topic_chain"],
+            _create_and_register_topic_chain(
                 topic=topic,
-                metadata=config.topics[topic],
-            )
-            config.topics[topic].update(
-                {
-                    "topic_chain": chain_instance,
-                }
+                topic_raw_cfg=topic_raw_cfg,
+                chain_factory=chain_factory,
             )
+
             logging.info(f"Added topic `{topic}`")
             logging.debug(f"`{topic}` configuration: `{topic_raw_cfg}`")
-
         except Exception as exc:
             logging.error(
                 f"Unable to load `{topic}` configuration with: {topic_raw_cfg}. "
@@ -135,4 +130,20 @@ async def lifespan(fastapi_app: fastapi.FastAPI):
     config.topics.clear()
 
 
+def _create_and_register_topic_chain(topic, topic_raw_cfg, chain_factory):
+    """
+    Small helper function to create instance of the topic chain and add to the config
+    """
+    chain_instance = chain_factory.get(
+        topic_raw_cfg["topic_chain"],
+        topic=topic,
+        metadata=config.topics[topic],
+    )
+    config.topics[topic].update(
+        {
+            "topic_chain": chain_instance,
+        }
+    )
+
+
 app = get_app()
diff --git a/tests/test_config.py b/tests/test_config.py
index 56bb1af5..a8f8e2b9 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -1,10 +1,11 @@
 import importlib
 import os
+from unittest.mock import patch
 
 import pytest
 
-from gen3discoveryai import config
-from gen3discoveryai.main import _override_generated_openapi_spec
+from gen3discoveryai import config, main
+from gen3discoveryai.main import _override_generated_openapi_spec, lifespan
 from gen3discoveryai.topic_chains.utils import get_from_cfg_metadata
 
 
@@ -21,6 +22,38 @@ def test_bad_config_metadata():
     os.chdir(os.path.dirname(os.path.abspath(__file__)).rstrip("/") + "/..")
 
 
+@pytest.mark.asyncio
+@patch("gen3discoveryai.main._create_and_register_topic_chain")
+async def test_bad_config_default_topic(create_and_register_topic_chain):
+    """
+    Test when config loading raises an error, either it's reraised if it's the default topic
+    """
+    create_and_register_topic_chain.side_effect = Exception("some expection")
+
+    with pytest.raises(Exception):
+        async with lifespan(main.app):
+            pass
+
+
+@pytest.mark.asyncio
+@patch("gen3discoveryai.main._create_and_register_topic_chain")
+async def test_bad_config_non_default_topic(create_and_register_topic_chain):
+    """
+    Test when config loading raises an error, either it's reraised if it's the default topic
+    """
+
+    def _exception_if_default(*args, **kwargs):
+        # simulate default topic being okay, e.g. don't raise error here
+        if kwargs.get("topic") == "default":
+            pass
+
+    create_and_register_topic_chain.side_effect = _exception_if_default
+
+    async with lifespan(main.app):
+        # we don't expect an exception for non default topics
+        assert True
+
+
 def test_metadata_cfg_util():
     """
     If it exists, return it