There’s an issue with one of the theme components you’re using. Enter safe-mode again, then go to admin > customize > components and look for Discourse Header Search
Once you click on that, disable it for now with this button.
Everything should work normally then, except you won’t have the search bar in the header. You should still have the magnifying icon - the default Discourse search.
You can then post on the theme’s topic, and I’m sure it will get fixed as soon as possible.
Once it’s fixed, you can update the component and then re-enable it.