Created attachment 288973 [details] [review]
Demonstrative assert

I've attached a diff to demonstrate this. The assert quickly fails with e.g. Shift+<A>.

The code seems to assume that `col` points to the base of the group's syms, but this does not hold after `found` becomes true and the loop continues. So in some cases the syms of the next group (if there one) or key (if there is one) are unintentionally accessed.

I am not entirely sure what was the exact intention of this line, i.e. whether the LHS or RHS of the `==` should change (the comment below is somewhat ambiguous), so I'll leave the fix for someone more familiar with the code.