Beware of Drupal's Radios FAPI empty handling

Did you ever switch a Drupal Form API element from "select" to "radios" and expect it would behave equally? You're wrong!
Here's (sadly) why...

Drupal 7 FAPI's #states: Take care of Internet Explorer (IE)!!! (Conditional fields not working in IE)

Today I ran into a very very mad bug: ‎Conditional Fields‎ did not correctly work in IE, as discussed in this issue:

But as I later found out and posted here this problem is based on the FAPI #states API!