fix: show error when configuration file path explicitely set but not found

main.py

@@ -21,6 +21,9 @@ class Config:
         if config_path.exists():
             with config_path.open("rb") as f:
                 config = tomllib.load(f)
+        elif "CONFIG_PATH" in os.environ:
+            print(f"Configuration file {config_path} does not exist; create it or change the CONFIG_PATH environment variable to another path")
+            exit(1)
         else:
             config = {}