Fix: Handle None metadata in Gemini pipeline to prevent AttributeError

When no filters are installed or Open WebUI doesn't provide the __metadata__
parameter, it can be None, causing "'NoneType' object has no attribute 'get'" error.

Added defensive check: metadata = __metadata__ or {}
This ensures metadata is always a dict, even when __metadata__ is None.

Co-authored-by: owndev <69784886+owndev@users.noreply.github.com>

Author: Claude

pipelines/google/google_gemini.py

@@ -1925,8 +1925,10 @@ def _configure_generation(
             gen_config_params |= {"safety_settings": safety_settings}
 
         # Add various tools to Gemini as required
-        features = __metadata__.get("features", {})
-        params = __metadata__.get("params", {})
+        # Handle case where __metadata__ might be None
+        metadata = __metadata__ or {}
+        features = metadata.get("features", {})
+        params = metadata.get("params", {})
         tools = []
 
         if features.get("google_search_tool", False):