Conditional dangerouslySetInnerHTML triggers Trusted Types violation

[lukewarlow]

• Check if updating to the latest Preact version resolves the issue

Describe the bug
If you conditionally apply dangerouslySetInnerHTML, Preact internal code leads to a TrustedTypes violation.

To Reproduce

If possible, please provide a link to a StackBlitz/CodeSandbox/Codepen project or a GitHub repository that demonstrates the issue. You can use the following template on StackBlitz to get started: https://stackblitz.com/edit/create-preact-starter

Steps to reproduce the behavior:

1. Go to https://codepen.io/lukewarlow/pen/wBMjmJM
2. Click on "Toggle HTML" twice
3. Open browser dev tools and see the Trusted Types violation (will need Chromium or Safari 26+)

Expected behavior
What should have happened when following the steps above?

The text should toggle between the two values.

[lukewarlow]

This is caused I believe by

preact/src/diff/index.js

Line 610 in 078ed0e

if (oldHtml) dom.innerHTML = '';

this should either not use innerHTML (I think just setting textContent = "" works)? Or it should use something like below (see emptyHTML docs)

if (oldHtml) dom.innerHTML = trustedTypes?.emptyHTML ?? '';