Possible bug in nemesis.cc

[Clownacy]

I don't know the first thing about C++, so I'm mainly just relaying what Visual Studio 2019 is telling me.

Apparently this line in nemesis.cc is wrong:

operator()(SizeFreqNibble const& lhs, SizeFreqNibble const& rhs) noexcept {

It gives me a 'C3848' error. Changing the line to this makes it go away:

operator()(SizeFreqNibble const& lhs, SizeFreqNibble const& rhs) const noexcept {