<button type="button"
oneclick="document.getElementById('a').style.visibility='visible'">
Click
</button>
<img id="a" style="visibility:hidden" src='pico.png' alt="src not found">

I mistyped "oneclick", but VS Code doesn't show me that. I was going crazy because I didn't find the error. Why? I already installed HTMLHint, HTML, CSS, Javascript extensions.