Now what’s up with that? You are humming along nicely and then suddenly your NPM/Yarn installs are breaking.
Yarn: No Xcode or CLT version detected!
Inspecting the error message, the problem appears to be with node-gyp, the part where C++ code is compiled for the module being installed.
For some reason, the issue appears to be related to a messed up Xcode environment due to the update and happens every time Xcode gets bumped up.
Fix ain’t pretty; multiple variants found across the web. Here is what worked for me (Catalina 10.15, Xcode 11.3):
sudo rm -rf $(xcode-select -print-path)
sudo npm install -g node-gyp
Not sure why Apple refuses to fix this, in spite of being a common problem. Developers are expected to do it the hard way, I suppose!