Julia can not start inside Atom

That Cannot read property 'classList' of undefined error is unrelated, unfortunately.

  1. Can you try restarting Atom, and then open the REPL tab

    and then just press Enter? You might get a more informative error message there.
  2. If that doesn’t help, try renaming C:\Users\user\.atom to C:\Users\user\.atom.bak, reinstall Juno and try again.