nits and earlier raising if model dir does not exist

arkindex_worker/worker/base.py

@@ -50,8 +50,6 @@ class ModelNotFoundError(Exception):
     Exception raised when the path towards the model is invalid
     """
 
-    pass
-
 
 class BaseWorker(object):
     """
@@ -105,7 +103,7 @@ class BaseWorker(object):
         # To load models locally
         self.parser.add_argument(
             "--model-dir",
-            help=("The path to a local model's directory. "),
+            help=("The path to a local model's directory (development only)."),
             type=Path,
         )
 
@@ -369,19 +367,19 @@ class BaseWorker(object):
             # downloads the model and set it in the current task work dir
             return Path(self.work_dir)
         else:
-            model_path = self.config.get("model_dir", self.args.model_dir)
-            if model_path is None:
+            model_dir = self.config.get("model_dir", self.args.model_dir)
+            if model_dir is None:
                 raise ModelNotFoundError(
                     "No path to the model was provided. "
                     "Please provide model_dir either through configuration "
                     "or as CLI argument."
                 )
-            if Path(model_path).exists():
-                return Path(model_path)
-            else:
+            model_dir = Path(model_dir)
+            if not model_dir.exists():
                 raise ModelNotFoundError(
-                    f"The path {model_path} does not link to any directory"
+                    f"The path {model_dir} does not link to any directory"
                 )
+            return model_dir
 
     @retry(
         retry=retry_if_exception(_is_500_error),