How to fix chatGPT API producing bad request error?

Question

I'm trying to simply print an answer in terminal to the "say hello" prompt, but it logs Error: Request failed with status code 400 to the terminal.

Here's the code that tries to use the ChatGPT API:

const axios = require('axios');

async function getChatGptResponse(prompt, apiKey, apiEndpoint) {
  const headers = {
    'Authorization': `Bearer ${apiKey}`,
    'Content-Type': 'application/json',
  };

  const data = {
    'messages': [{'role': 'user', 'content': prompt}],
  };

  try {
    const response = await axios.post(apiEndpoint, data, { headers });
    return response.data.choices[0].message.content;
  } catch (error) {
    console.error('Error:', error.message);
    return null;
  }
}

async function main() {
  const apiKey = 'myKey'; // Replace this with your actual API key
  const apiEndpoint = 'https://api.openai.com/v1/chat/completions';

    const prompt = "say hello";

    const response = await getChatGptResponse(prompt, apiKey, apiEndpoint);
    if (response) {
      console.log('ChatGPT:', response);
    }

}

main();