I did a fresh reinstall (removing chia-blockchain folder then following the ubuntu install instructions) and everything runs smoothly until I run sh install-gui.sh to which I get this error.
The picture above shows the error message and the actual code has hundreds of lines of “npm WARN tar ENOENT: no such file or directory, open '…/chia-blockchain-gui/node_modules/…”
Hope this is clear enough, and appreciate it if anyone can help! 
Did you notice this at the github install instructions: # You can not install and run the GUI as root
Are you running as root or su to its privileges?
Otherwise did you mean to (re)install or upgrade your earlier config? There’s are separate instructions for both?
If all fails you can use the ‘one-click’ installer for Ubuntu from chia.net Downloads.
Actually it’s three clicks, you first have to save the installer on disk, then run it from there. Invoking the package installer straight from the download will cause an error.
The installer does not install to ~/chia-blockchain. It goes to /usr/lib/chia-blockchain/…
CLI is at /usr/lib/chia-blockchain/resources/app.asar.unpacked/daemon and starts with ./chia.
./chia version for example.
GUI is based on an Electron JavaScript framework. The components are sourced via NPM.
My guess is that some of the packages are only available through non-standard git repository of some sorts, and cannot be checked out publicly