code: def test_chat_message_list_with_mixed_object_list(self):
      prompt_builder = DynamicChatPromptBuilder(
          runtime_variables=["documents"]
      )
  
      with pytest.raises(ValueError):
          prompt_builder._process_chat_messages(
              prompt_source=[
                  ChatMessage.from_user("Hello"),
                  "there world",
              ],
              template_variables={},
          )
  
file_path: haystack/test/components/builders/test_dynamic_chat_prompt_builder.py
imports: from typing import List
  import pytest
  from haystack import Pipeline
  from haystack.components.builders import DynamicChatPromptBuilder
  from haystack.dataclasses import ChatMessage
label_desc: Use image node_id 5 for calling the TestDynamicChatPromptBuilder obj's underlying member method code with example usage: obj.test_chat_message_list_with_mixed_object_list() without return types