Resolves a valid URL string - which may potentially be a relative-URL string - with the current object as the base URL.
Parameters
uri
A valid URL string (e.g. /foo or https://example.com/foo) to apply on
the current object.
softErrors
An array to pass a list of Uri\WhatWg\UrlValidationError
instances by reference to provide extended information about the soft errors triggered during reference resolution.