"There are mostly warm clothes here."
Translation:Hier zijn vooral warme kleren.
Not neccissairily. But if you want to use it, the only correct way to do it is: 'Hier zijn er vooral warme kleren'.
Disagree - I'd even argue it's not correct, as in I would never use it in a formal setting/written text. As I said it's common in spoken Dutch, but definitely not 'the only correct way to do it'.
No, you don't. If you really want to, you could say 'hier zijn er vooral warme kleren' which reads a bit weird but it's common in spoken Dutch. Using 'er' + inversion would also be correct, as in 'er zijn hier vooral warme kleren' but it's not necessary.
Thank you! So your second sentence is what I was expecting it to be (i.e. 'er zijn hier...'). Does that sound natural? I'm a bit confused since you two disagree!
Yep, that sounds natural, though it shifts the emphasis to the clothes rather than the place, since 'hier' is no longer at the start of the sentence.
'Er' is a confusing little thing, as in almost no one really knows when (not) to use it; native speakers get it wrong all the time (and for that reason I try to avoid 'er' when writing formal emails/essays/etc). The formal rules are a bit ambiguous, but generally if you think of 'er' as the Dutch equivalent of 'there' and the sentence stops making sense, you should leave it out. That's why 'hier zijn er' is not quite right- just like in English, you can say 'there are clothes here' but not 'here are there clothes'.