Fix error with long messages breaking for everyone

Author: Alex-Welsh

web-apps/chat/app.py

@@ -70,7 +70,7 @@ def inference(latest_message, history):
         context = []
         if INCLUDE_SYSTEM_PROMPT:
             context.append(SystemMessage(content=settings.model_instruction))
-        else:
+        elif history and len(history) > 0:
             # Mimic system prompt by prepending it to first human message
             history[0]['content'] = f"{settings.model_instruction}\n\n{history[0]['content']}"