Fix multiple runtime errors

- `firebase_admin._auth_utils._parse_error_body`: AttributeError: 'str' object has no attribute 'get'
- `firebase_admin._http_client.HttpClient.headers`: TypeError: 'ABCMeta' object is not subscriptable
- `firebase_admin.db.Reference.__init__`: ValueError: Invalid path: "None". Path must be a string.
- `firebase_admin.functions.TaskQueue._validate_task_options`: TypeError: isinstance() arg 2 must be a type, a tuple of types, or a union
- `firebase_admin.ml.Model._convert_to_millis`: TypeError: can't subtract offset-naive and offset-aware datetimes

Author: ViktorSky

firebase_admin/_auth_utils.py

@@ -619,8 +619,11 @@ def _parse_error_body(response: requests.Response) -> typing.Tuple[typing.Option
         return None, None
 
     # Auth error response format: {"error": {"message": "AUTH_ERROR_CODE: Optional text"}}
-    parsed_body = typing.cast(typing.Dict[str, typing.Dict[str, str]], parsed_body)
+    parsed_body = typing.cast(typing.Dict[str, typing.Any], parsed_body)
     error_dict = parsed_body.get('error', {})
+    if not isinstance(error_dict, dict):
+        return None, None
+    error_dict = typing.cast(typing.Dict[str, str], error_dict)
     code, custom_message = error_dict.get('message'), None
     if code:
         separator = code.find(':')

firebase_admin/_http_client.py

@@ -154,7 +154,7 @@ class call this method to send HTTP requests out. Refer to
         resp.raise_for_status()
         return resp
 
-    def headers(self, method: str, url: str, **kwargs: typing.Any) -> requests.structures.CaseInsensitiveDict[str]:
+    def headers(self, method: str, url: str, **kwargs: typing.Any) -> 'requests.structures.CaseInsensitiveDict[str]':
         resp = self.request(method, url, **kwargs)
         return resp.headers
 

firebase_admin/db.py

@@ -186,7 +186,7 @@ def __init__(
         Reference.
         """
         self._client = client
-        if segments:
+        if segments is not None:
             self._segments = segments
         else:
             self._segments = _parse_path(path)

firebase_admin/functions.py

@@ -249,7 +249,7 @@ def _validate_task_options(
                 raise ValueError(
                     'Both sechdule_delay_seconds and schedule_time cannot be set at the same time.')
             if opts.schedule_time is not None and opts.schedule_delay_seconds is None:
-                if not isinstance(opts.schedule_time, datetime):
+                if not isinstance(opts.schedule_time, datetime.datetime):
                     raise ValueError('schedule_time should be UTC datetime.')
                 task.schedule_time = opts.schedule_time.strftime('%Y-%m-%dT%H:%M:%S.%fZ')
             if opts.schedule_delay_seconds is not None and opts.schedule_time is None:

firebase_admin/ml.py

@@ -287,7 +287,7 @@ def _convert_to_millis(date_string: typing.Optional[str]) -> typing.Optional[int
             return None
         format_str = '%Y-%m-%dT%H:%M:%S.%fZ'
         epoch = datetime.datetime.fromtimestamp(0, datetime.timezone.utc)
-        datetime_object = datetime.datetime.strptime(date_string, format_str)
+        datetime_object = datetime.datetime.strptime(date_string, format_str).replace(tzinfo=datetime.timezone.utc)
         millis = int((datetime_object - epoch).total_seconds() * 1000)
         return millis