RC.0: ionic build browser fails

I have a copy of the hello-world starter project in a git repo. I’ve cloned it to another machine and am trying to compile it. I’ve made sure node/npm are the same version on both machines.
After cloning I’ve done:

npm install
ionic state reset

Now when I go to build the project for the browser (only build I’ve tried as of yet) it errors out:

$ ionic build browser

Running ‘build:before’ npm script before build

ionic-hello-world@ build /Users/beck24/ionic
ionic-app-scripts build
[22:30:48] ionic-app-scripts 0.0.23
[22:30:48] build prod started …
[22:30:48] clean started …
[22:30:48] clean finished in 10 ms
[22:30:48] copy started …
[22:30:48] ngc started …
[22:30:48] lint started …
[22:30:48] copy finished in 77 ms

[22:30:48] bundle prod started …
[22:30:48] Error: Could not resolve entry (.tmp/app/main.prod.js)
at /Users/beck24/ionic/node_modules/rollup/dist/rollup.js:8602:28

any suggestions?

I should note that in .tmp/app/ there is a main.prod.ts file, not .js
The project was created initially as a ts (by default) and builds properly on the original machine. Why is it looking for .js?

The ionic.config.json is:

  "name": "ionic",
  "app_id": "",
  "v2": true,
  "typescript": true