fix: Handle empty GenerateMemories response (no memories generated) as valid response.

PiperOrigin-RevId: 802295630

Author: vertex-sdk-bot

vertexai/_genai/memories.py

@@ -1284,10 +1284,8 @@ def generate(
                 operation_name=operation.name,
                 get_operation_fn=self._get_generate_memories_operation,
             )
-            if not operation.response:
-                if operation.error:
-                    raise RuntimeError(f"Failed to generate memory: {operation.error}")
-                raise RuntimeError(f"Error generating memory: {operation}")
+            if operation.error:
+                raise RuntimeError(f"Failed to generate memory: {operation.error}")
         return operation
 
     def list(