we cant use optional refs in useMergeRef

I think it's better we can use optional ref, sometimes you want to get some optional ref from props so you cant use the current useMergeRef for this!

so change the refs argument to optional and use a filter before "for".

Start at the useMergeRef entry point and inspect how its refs argument is iterated. Update the behavior so optional refs can be passed and are excluded before iteration; done means callers can omit a ref without failure while existing ref merging still works.

Written by the indexing model from the issue text.