use config validation for healthcheck

app/tests/test_config.py

@@ -2,6 +2,7 @@
 import tomllib
 from schema import SchemaMissingKeyError
 from app.src.config import Config
+from typing import Tuple
 
 class TstConfig(Config):
 
@@ -10,8 +11,8 @@ class TstConfig(Config):
         cls.config = cnf
 
     @classmethod
-    def _read_config_file(cls) -> dict:
-        return cls.config
+    def _read_config_file(cls) -> Tuple[dict, str| None]:
+        return cls.config, None
 
 
 def test_empty_config():