Prior to the app installer saying the app had been successfully installed (and the app now appearing in the menu bar), I received this error:
Not sure if I need to re-do something or all is well?
tl;dr: if the app launched and works for you, it's probably fine.
tl;wr: Installing kernel extensions is tricky. I should probably just require a restart during the install process, as that seems to solve many of those problems.
Otherwise, I've seen this error message during development when the kernel extension had faulty permissions set.
What version of WavTap did you install?
What version of OSX are you running?
What do you see when you run this:
sudo kextutil -v --print-diagnostics /System/Library/Extensions/WavTap.kext/
Here's what I get:
No kernel file specified, using '/mach_kernel'
/System/Library/Extensions/WavTap.kext appears to be loadable (not including linkage for on-disk libraries).
/System/Library/Extensions/WavTap.kext successfully loaded (or already loaded).