Your API request is returning a text/html webpage:
<!doctype html><html lang="en"><head><meta charset="utf-8"/><meta name="viewport" content="width=device-width,initial-scale=1,shrink-to-fit=no"/><meta name="theme-color" content="#000000"/><link rel="manifest" href="/manifest.json"/><link rel="shortcut icon" href="/favicon.ico"/><title>Gitter Search</title><link href="/static/css/main.0ac613d8.css" rel="stylesheet"></head><body><noscript>You need to enable JavaScript to run this app.</noscript><div id="root" class="app-container"></div><script src="/static/js/main.2287eacc.js"></script></body></html>