title: Why TypeScript lets me add a string and a number? Can I prevent it?
body: <p>The following code</p>
  
  <pre><code>let k = "1";
  k += 1;
  console.log(k);
  </code></pre>
  
  <p>compiles correctly using TypeScript, even in strict mode. I would have expected tsc to fail with some error like <code>Cannot add a string and an integer.</code>. Why does it build successfuly? Can I prevent this dangerous behavior?</p>