title: fatal error: high- and low-surrogate code points are not valid Unicode scalar values
body: <p>Sometimes while initializing a <code>UnicodeScalar</code> with a value like <code>57292</code> yields the following error:</p>
  
  <pre><code>fatal error: high- and low-surrogate code points are not valid Unicode scalar values
  </code></pre>
  
  <p>What is this error, why does it occur and how can I prevent it in the future?</p>