added exception in case model (#48)

Author: TLSDC

src/agentlab/llm/chat_api.py

@@ -251,8 +251,15 @@ def __init__(
         # Get pricing information
         if pricing_func:
             pricings = pricing_func()
-            self.input_cost = float(pricings[model_name]["prompt"])
-            self.output_cost = float(pricings[model_name]["completion"])
+            try:
+                self.input_cost = float(pricings[model_name]["prompt"])
+                self.output_cost = float(pricings[model_name]["completion"])
+            except KeyError:
+                logging.warning(
+                    f"Model {model_name} not found in the pricing information, prices are set to 0. Maybe try upgrading langchain_community."
+                )
+                self.input_cost = 0.0
+                self.output_cost = 0.0
         else:
             self.input_cost = 0.0
             self.output_cost = 0.0