I get an exception when I have a GroupBy and a var named 'group' and follow R# advice to convert into a LINQ expression. Simplest case example:
foreach (var group in new int.GroupBy(n => n))
var x = group.Key;
if (x == 1) return;
The 'foreach' has a squiggly under it. If I choose to convert into a LINQ expression then I will get the null reference exception.
The workaround is to rename 'group' to something else like 'group0'. Then it works fine.
This is with R# 5.1.1753.3.