Hello,
I see the same compile error with svn-12556. Here I use ubuntu-20.04 as well as arch linux and
compile cb as usual per command-line, configure and make.
Although the symbol cbDEBUG might be missing in some project(s), IMHO
cbAssertNonFatal should be handled in file src/include/cbexception.h in the same way cbAssert is.
mainly:
#ifndef cbDEBUG
#define cbAssertMessage(expr)
#define cbAssertNonFatal(expr)
#define cbAssert(expr)
#else
Or maybe define them like en.cppreference.com/w/cpp/error/assert.
A patch for the file is attached.
Thanks in advance.