Ionic 3: Build in “prod” mode: Cannot find module “.”

I found the problem. In my package.json I was using:

"typescript": "^2.9.1",

Decreasing the version to ~2.6.2 fixed it for me.

Removing ^ from @ionic/app-scripts and typescript works for me as follows:

"devDependencies": {
    "@ionic/app-scripts": "3.1.9",
    "typescript": "2.8.3"
  }

I had a similar problem, but the wrong typescript package was getting pulled in from a combination of other dependent projects as well as VS Code. I resolved it by pinning the exact version (no ^ or ~) of @ionic/app-scripts and typescript to what I needed.

"devDependencies": { "@ionic/app-scripts": "3.1.9", "typescript": "2.6.2" }