title: How to make the page not break when api call, when you are not in IP allowlist(ip4 address is not in whitelist)
body: <p>I am building a React webpage with login function. Please see the attached picture.</p>
  <p><img src="https://i.stack.imgur.com/3nlap.jpg" alt="login form" /></p>
  <p>The login requires user's email address and will send a code to the email, then user could successfully logged in after submit the code in the login form.
  My instructor stores my IP4 address in the whitelist, so that when I login in then can successfully make an api call.
  But now the question is how to make the page not break when api call, when users are not in IP allowlist(ip4 address is not in whitelist).
  I have a hint that is replacing the real api call using mock data or doing something in catch exception.</p>