Fix case where model path is set but not labelmap path

frigate/util/builtin.py

@@ -9,7 +9,7 @@ import urllib.parse
 from collections import Counter
 from collections.abc import Mapping
 from pathlib import Path
-from typing import Any, Tuple
+from typing import Any, Optional, Tuple
 
 import numpy as np
 import pytz
@@ -139,7 +139,7 @@ def get_ffmpeg_arg_list(arg: Any) -> list:
     return arg if isinstance(arg, list) else shlex.split(arg)
 
 
-def load_labels(path, encoding="utf-8", prefill=91):
+def load_labels(path: Optional[str], encoding="utf-8", prefill=91):
     """Loads labels from file (with or without index numbers).
     Args:
       path: path to label file.
@@ -147,6 +147,9 @@ def load_labels(path, encoding="utf-8", prefill=91):
     Returns:
       Dictionary mapping indices to labels.
     """
+    if path is None:
+        return {}
+
     with open(path, "r", encoding=encoding) as f:
         labels = {index: "unknown" for index in range(prefill)}
         lines = f.readlines()