I don't know about Gap closer, how can fill the gaps in scaffolds?
You can take a look at the papers mentioned in this answer: A: Post Assembly Gap Filling
If you are able to (see section around 17:00 min):
but I read these comments, isn't clear for me, and isn't my question response.
This paper has a nice schematic (Figure 2) on how gaps are filled.
Thank you for your help.