Angular 2 recently changed the build mechanism from SystemJS to Webpack in the latest version. This may be one (among others) of the reasons for this error message (it was for me anyway).
, , git, :
npm uninstall -g angular-cli
npm cache clean
npm install -g angular-cli@latest //in theory, npm install -g angular-cli should be OK
, , "", , node_modules :
rm -rf node_modules
npm install
:
ng build