Salaam,
This is not a typo, but a font issue. When Kasra follows Shaddah, some fonts
decide to show Kasra over the base letter and under Shaddah. See this:
http://tanzil.net/wiki/Arabic_fonts_issues
Because of many false typo reports we render Kasra before Shaddah, so the
Kasra should always be d
In surah An-Nisaa verse 86 there is a typo in the Arabic. It should be
"Waitha huyyeetum". There should be a kasra instead of fatha in
حُيِّيتُم. I hope I am clear. Wallah u Alam.
P.S I checked the Tanzil Quran navigator which shows the same as zekr
but "http://quran.com/4"; shows a kasra. Any he