Extension gives this error: Either the 'unsafe-inline' keyword, a hash ('sha256-...'), or a nonce ('nonce-...') is required to enable inline execution

Question

I'm trying to make a simple extension to change a website's favicon, but i get this error:

Either the 'unsafe-inline' keyword, a hash ('sha256-...'), or a nonce ('nonce-...') is required to enable inline execution.

This is the button that caused the error when I pressed it:

   <button id="Change" onclick="change()">Change Favicon</button>

And the javascript:

function change(){
document.querySelector('link[rel*="icon"]').href =" //placehold.it/32/F00"
}