Jules,
the Mac and Linux platform specific implementations of
File::isOnRemovableDrive()
are missing for Linux and Mac.
Easy enough to fix at my end, but probably should be fixed on the tip. 
Ah, I didn’t realise that was still waiting to be done. I’ll get onto it.
Would be nice to have that one, I also got the compilation error just now on the Mac 
heh, and me too again, just now…
This is Juce off the tip, BTW.