Illegal argument undefined

Updated my development site to Kirby 4.0.0 running on Mac OS / MAMP Pro and my production site, to find that every page in Panel is popping up an error message “Illegal argument undefined”. I tried various things to resolve this including a fresh install locally of Starter Kit v4 which also gave the same result. I then tried a different browser and the message did not show. With Safari I get this message, with Chrome or Firefox I don’t.

No big deal as I will not use Safari but would be interested to know if this is just an issue with my setup ? Searched here and Google but can’t see mention of it from anyone else.

What version of Safari is that?

I think there are currently some issues with Safari, but don’t think this is one of them. I could not reproduce this issue with a fresh Kirby 4 Starterkit and Safari Version 17.0 (19616.1.27.211.1)

I have Version 17.1 (19616.2.9.11.7) on macOS Sonoma 14.1.1 (23B81)

Thanks