Cannot run server on mac

[dylan-chong]

I followed the install instructions on the readme and...

> mix phoenix.server
warning: variable "deps" does not exist and is being expanded to "deps()", please use parentheses to remove the ambiguity or change the variable name
  mix.exs:12

[info] Running Battleship.Endpoint with Cowboy using http://localhost:4000
09:50:23 - error: Initialization error - You probably need to execute `npm install` to install Brunch plugins.
Error: Cannot find module '../modules/web.dom.iterable' You probably need to execute `npm install` to install Brunch plugins.
Error: Cannot find module '../modules/web.dom.iterable'
Stack trace was suppressed. Run with `LOGGY_STACKS=1` to see the trace.