Wikipedia Disambiguation page causes, "promises.js:47 TypeError: Cannot read property 'source' of undefined"... Fix?

function generateHTML(data) {
  data.forEach( person => {
    const section = document.createElement('section');
    peopleList.appendChild(section);
    // Check if request returns a 'standard' page from Wiki
    if (person.type === 'standard') {
      section.innerHTML = `
        <img src=${person.thumbnail.source}>
        <h2>${person.title}</h2>
        <p>${person.description}</p>
        <p>${person.extract}</p>
      `;
    } else {
      section.innerHTML = `
        <img src="img/profile.jpg" alt="ocean clouds seen from space">
        <h2>${person.title}</h2>
        <p>Results unavailable for ${person.title}</p>
        ${person.extract_html}
      `;
    }
  });
}