Can't install

[ywhcuhk]

Both in GUI and Command line, I can't install the package. Command line log is following

npm WARN addRemoteGit git://github.com/cs150bf/inline-css.git resetting remote /Users/wy/.atom/.apm/_git-remotes/git-github-com-cs150bf-inline-css-git-4e6d75d6 because of error: xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
npm ERR! git clone --template=/Users/wy/.atom/.apm/_git-remotes/_templates --mirror git://github.com/cs150bf/inline-css.git /Users/wy/.atom/.apm/_git-remotes/git-github-com-cs150bf-inline-css-git-4e6d75d6: xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
npm ERR! Darwin 15.0.0
npm ERR! argv "/Applications/Atom.app/Contents/Resources/app/apm/bin/node" "/Applications/Atom.app/Contents/Resources/app/apm/node_modules/npm/bin/npm-cli.js" "--globalconfig" "/Users/wy/.atom/.apm/.apmrc" "--userconfig" "/Users/wy/.atom/.apmrc" "install" "/private/var/folders/v_/5vfmh4w11h59htq4w791l_5r0000gp/T/d-1151025-22502-1v9mfd8/package.tgz" "--target=0.34.0" "--arch=x64"
npm ERR! node v0.10.40
npm ERR! npm  v2.13.3
npm ERR! code 1

npm ERR! Command failed: xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
npm ERR!
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR!     <https://github.com/npm/npm/issues>

npm ERR! Please include the following file with any support request:
npm ERR!     /private/var/folders/v_/5vfmh4w11h59htq4w791l_5r0000gp/T/apm-install-dir-1151025-22502-han8j3/npm-debug.log

[cs150bf]

I tried googling "Command failed: xcrun: error: invalid active developer path" and here are some results I found:

• https://github.com/atom-minimap/minimap/issues/103
• https://github.com/Homebrew/homebrew/issues/23500
• http://apple.stackexchange.com/questions/209624/how-to-fix-homebrew-error-invalid-active-developer-path-after-upgrade-to-os-x
• http://i-broke-it.blogspot.com/2013/10/fixing-xcrun-error-invalid-active.html

Even though I'm not sure how exactly this issue happens...