Why graphql query doesn't work in react?

It stopped working because the user might not have such information.

I cloned your repo and added the code

<div>email:{user.following.email}</div>

It did stop working then I added a fallback

<div>email:{user.following.email || ""}</div>

It worked.

You might want to check this information before rendering, e.g.

{user && user.following && user.following.email &&
  (<div>email:{user.following.email}</div>)
}

The same thingorganizations

<p>
  {user && user.organizations &&
    <div>Organization name:{user.organizations.name}</div>
  }
</p>

As for followers( updated )

const Followers = ({ followers }) => (
<div>

  <strong>Followers updated for SO:</strong>

  <ul>
    {followers.edges.map(follower => (
    <li key={follower.node.id}>
      <img src={follower.node.avatarUrl}/>
      <div>
        {follower && follower.node && follower.node.name && (
        <div>Name:{follower.node.name}</div>) }
      </div>
      <div>
        {follower && follower.node && follower.node.email && (
        <div>Email:{follower.node.email}</div>) }
      </div>
    </li>
    ))}
  </ul>
</div>
);

Screenshot of my profile. One has email followers, the other doesn't.

I went ahead and forked your repo, which is a clone of my repo from your question. Make sure your token has the permissions. On a whim, I can totally use my keys. Check yours!