There are no errors in the Qur'an because there are no facts in the Qur'an.
So, really, both sides are right and wrong at the same time. Just think about it. The Qur'an is not a book of science; it's not a book of history; it's not a book of astronomy; it's not a book of math; it's not a cookbook; it's not a book on the history of cruci-fiction or non-fiction; and etc. That's not the intentions of it. So there's no point in holding anything in it up to those standards. Just as there's no point in defending things in it by those standards. To even say there are facts in the Qur'an is to reduce it to a mere textbook. And to say there are errors in it is to misunderstand it.
I think the Qur'an is profoundly true, but not factual. This doesn't take anything away from it. It's true as metaphorical or symbolic narrative.
Buddhists often speak of the teaching of the Buddha as "a finger pointing to the moon." The metaphor helps guard against the mistake of thinking that being a Buddhist means believing in Buddhist teaching--that is, believing in the finger. As the metaphor implies, one is to see (and pay attention to) that to which the finger points.
To apply the metaphor to the Qur'an, the Qur'an is like a finger pointing to the moon. Muslims sometimes make the mistake of thinking that being Muslim is about believing in the finger rather than seeing the Muslim life as a relationship to that which the finger points.
To use another metaphor, the Qur'an is like a lens. There's a crucial difference between believing in the lens and using the lens as a way of seeing that which is beyond the lens.