Gnats in indoor compost bin

So my worm compost bin in my kitchen is swarming with little gnats. They are mostly inside but there are also a few on the surrounding wall and sides of bin.

I have only been doing this for a few weeks and was really excited for free fertilizer and a greener way of disposing plant waste of which we have a lot.

Is there anything I can do about this? Do they harm the worms and composting? Should I just let it be or will it get worse? Would it do better outside? (I live in an apartment building so putting it outside would be tricky but possible)

Thanks