Fix some errors found in calc examples

mm_agents/gpt_4v_agent.py

@@ -505,6 +505,7 @@ class GPT4v_Agent:
     @backoff.on_exception(
         backoff.expo,
         (APIError, RateLimitError, APIConnectionError, ServiceUnavailableError, InvalidRequestError),
+        max_tries=3
     )
     def call_llm(self, payload):
         response = requests.post(
@@ -514,6 +515,18 @@ class GPT4v_Agent:
         )
 
         if response.status_code != 200:
+            if response.json()['error']['code'] == "context_length_exceeded":
+                print("Context length exceeded. Retrying with a smaller context.")
+                payload["messages"] = payload["messages"][-1:]
+                retry_response = requests.post(
+                    "https://api.openai.com/v1/chat/completions",
+                    headers=self.headers,
+                    json=payload
+                )
+                if retry_response.status_code != 200:
+                    print("Failed to call LLM: " + retry_response.text)
+                    return ""
+
             print("Failed to call LLM: " + response.text)
             return ""
         else: