fix: test value for existence before checking

Author: koebi

ORStools/common/client.py

@@ -85,7 +85,7 @@ def __init__(self, provider: Optional[dict] = None, agent: Optional[str] = None)
         self.settings = QgsSettings()
         self.user_agent = self.settings.value("qgis/networkAndProxy/userAgent")
         # In case the value was still set by the ORS Tools Plugin, reset to empty string
-        if "ORStools" in self.user_agent:
+        if self.user_agent and "ORStools" in self.user_agent:
             self.user_agent = ""
         self.settings.setValue("qgis/networkAndProxy/userAgent", agent)
 
@@ -111,8 +111,6 @@ def _request(
         :rtype: QgsNetworkReplyContent
         :raises: Various ApiError exceptions based on HTTP status codes
         """
-        
-
 
         if post_json is not None:
             result = blocking_request.post(request, json.dumps(post_json).encode())
@@ -202,14 +200,12 @@ def fetch_with_retry(
                 # Reset to old value
                 self.settings.setValue("qgis/networkAndProxy/userAgent", self.user_agent)
 
-
         # Write env variables if successful
         if self.ENV_VARS:
             for env_var in self.ENV_VARS:
                 header_value = reply.rawHeader(self.ENV_VARS[env_var].encode()).data().decode()
                 configmanager.write_env_var(env_var, header_value)
 
-
         return json.loads(content)
 
     def get_delay_seconds(self, retry_counter: int) -> int: