Fail loudly if eslint command is not found
Fail loudly if eslint command is not found

Some people might be trying to use the fix imports feature without
having ESLint installed. This commit will make it apparent that this is
the case by failing loudly.

trotzig/import-js,trotzig/import-js,lencioni/import-js,lencioni/import-js,trotzig/import-js,Galooshi/import-js,lencioni/import-js