Cannot find type definition file for '@types'

Hi,

I am trying to build my app with the --prod flag.

ionic cordova build android --verbose --prod

However, when I do, I get the error:

typescript error 
            Cannot find type definition file for '@types'. 

[17:12:58]  ionic-app-script task: "build" 
[17:12:58]  Error: Failed to transpile TypeScript 
Error: Failed to transpile TypeScript

The app builds fine in release, but not prod.

Any ideas would be appreciated.