error on launch when i send message about gpt4-pdf-chatbot-langchain HOT 1 CLOSED

{chatMessages.map((message, index) => {
  // ...
  return (
    <>
      <div key={`chatMessage-${index}`} className={className}>
        {icon}
        <div className={styles.markdownanswer}>
          <ReactMarkdown linkTarget="_blank">
            {message.message}
          </ReactMarkdown>
        </div>
      </div>
      // ...

{message.sourceDocs.map((doc, index) => (
  <div key={`sourceDoc-${index}`}>
    <AccordionItem value={`item-${index}`}>
      <AccordionTrigger>
        <h3>Source {index + 1}</h3>
      </AccordionTrigger>
      <AccordionContent>
        <ReactMarkdown linkTarget="_blank">
          {doc.pageContent}
        </ReactMarkdown>
        <p className="mt-2">
          <b>Source:</b> {doc.metadata.source}
        </p>
      </AccordionContent>
    </AccordionItem>
  </div>
))}