tin-summer counts hardlinks twice

[sharkdp]

How to reproduce:

In an empty directory, create a 1MB file and a hard link to it:

dd if=/dev/zero bs=1M count=1 > file
ln file hardlink

sn now reports a total size of 2 MB:

▶ sn files -a
1.0  MB	 ./hardlink
1.0  MB	 ./file
2.0  MB	 .

Whereas it should rather be 1 MB:

▶ du -sh                
1,0M	.