fix assert used

core/agent.py

@@ -71,7 +71,8 @@ class BaseAgent(Agent):
         """Run a single interaction with the agent."""
         if self.model is None:
             await self.initialize()
-        assert self.model is not None
+        if self.model is None:
+            raise RuntimeError("Model initialization failed: model is None")
 
         messages: list[dict[str, str]] = [
             {"role": "system", "content": self.system_prompt},
@@ -91,7 +92,8 @@ class BaseAgent(Agent):
         """Run the agent with tool calling capability."""
         if self.model is None:
             await self.initialize()
-        assert self.model is not None
+        if self.model is None:
+            raise RuntimeError("Model initialization failed: model is None")
 
         try:
             capture = _ActResponseCapture()