Given there is a website measurable with at least one url in the "URLs" setting.
Now if I try to remove this URL (save the setting empty). It will appear to work. but after reloading the config page, it is clear that the "URLs" setting has still the old value.
This makes it impossible to save "URL"s with an empty value, if it is non-empty.
The documentation does not say this is impossible, nor is an error thrown, so this should be a bug.
Does it work when you comment this exception? https://github.com/matomo-org/matomo/blob/3.10.0-b3/plugins/WebsiteMeasurable/Settings/Urls.php#L74
Not sure why we are checking for a URL, I think it is not needed anymore.