I am creating a web extension which “scans” the page and uses results to form a response, here is my code:

function scanAndSummarizeWebpage() {
  chrome.tabs.query({ active: true, currentWindow: true }, function(tabs) {
    const activeTab = tabs[0];
    chrome.scripting.executeScript({
      target: { tabId: activeTab.id },
      function: getWebsiteContent
    }, function(results) {
      const websiteContent = results[0].result;
      console.log(websiteContent);
      alert (websiteContent);

       const endpoint = 'https://api.openai.com/v1/chat/completions';
       const data = {
         messages: [
           { role: 'system', content: 'You are a helpful assistant.' },
           { role: 'user', content: websiteContent },
           { role: 'assistant', content: 'Summarise this webpage.'}
         ],
         max_tokens: 282,
         temperature: 0.3,
         model: 'gpt-3.5-turbo',
         n: 1,
      };

I’ve tried running it through postman and it only shows an error message: “We could not parse the JSON body of your request. (HINT: This likely means you aren’t using your HTTP library correctly. The OpenAI API expects a JSON payload, but what was sent was not valid JSON. If you have trouble figuring out how to fix this, please contact us through our help center at help.openai.com.)”