fix: introduction key error (#221)

api/core/conversation_message_task.py

@@ -80,7 +80,10 @@ class ConversationMessageTask:
             if introduction:
                 prompt_template = OutLinePromptTemplate.from_template(template=PromptBuilder.process_template(introduction))
                 prompt_inputs = {k: self.inputs[k] for k in prompt_template.input_variables if k in self.inputs}
-                introduction = prompt_template.format(**prompt_inputs)
+                try:
+                    introduction = prompt_template.format(**prompt_inputs)
+                except KeyError:
+                    pass
 
             if self.app_model_config.pre_prompt:
                 pre_prompt = PromptBuilder.process_template(self.app_model_config.pre_prompt)