tr: handle empty yaml files correctly

Treat empty yaml files as valid empty dictionaries.

Signed-off-by: Omer Caspi <omer.caspi@gmail.com>

Author: omercsp

src/tr/config.py

@@ -121,7 +121,7 @@ def _read_config_file(file_path: str) -> ConfigFileModel:
             if ext == ".json":
                 data: dict = json.load(open(file_path, 'r'))
             elif ext == ".yaml" or ext == ".yml":
-                data: dict = yaml.safe_load(open(file_path, 'r'))
+                data: dict = yaml.safe_load(open(file_path, 'r')) or {}
             else:
                 raise TaskException("Unsupported configuration file format")
             return validate_config_file_schema(data)