Fresnel node inconsistencies

It seems that plugging the node, for example, directly into a colour output like 'Emission' or 'Transmission' causes a compile error ("'constructor': too many arguments"), while doing so via a relay node (or attaching other things that output scalar numbers), works. Fairly minor bug in terms of impact, but oddly inconsistent.

I also found earlier that disconnecting the 'Exp' input after it had been connected was causing the node previews to render only black (although the actual shader was ok). I can't reproduce that now, maybe it was fixed in an update.