working v2.1.4 - https://jsfiddle.net/7eje1znn/
not working v2.1.5 - https://jsfiddle.net/74zsdfv5/
Just open fiddle with v2.1.5 and check the console.
Well it should work without throwing exception since I don't see any breaking changes in this new release regarding render function.
It seems that Vue suddenly doesn't accept false value in array of children vnodes.. And if we change this line:
labelLeft && label
to labelLeft ? label : null
labelLeft ? label : null
then everything works correctly. No Error.
Seems that [false] node is not normalized
fix shipped in 2.1.6.