production mode build fails when using packages with scss and @import

[ahmed-anas]

I'm submitting a ... (check one with "x")

[x] bug report => check the README and search github for a similar issue or PR before submitting
[ ] support request => check the README and search github for a similar issue or PR before submitting
[ ] feature request

Current behavior
using a package like ngx-chips with scss files having @import gives an error unexpected character @ only when building in production mode
Expected/desired behavior
should work

Minimal reproduction of the problem with instructions

• install ngx-chips view npm install ngx-chips -S
• include the minimal template in home.component.ts: <tag-input [(ngModel)]='tags'></tag-input>
• add an tags array to home.component.ts
• include TagInputModule to home.module.ts from ngx-chips
• build in prod mode with either npm run build:spa-prod or npm run build:universal-prod

Please tell us about your environment:
vs code, windows 10

• Browser: all

• Node (for AoT issues): node --version = 7.8.0

[fulls1z3]

@ahmed-anas I'll have a look on this on the first opportunity, and many thanks for your contributions 👍

[fulls1z3]

@ahmed-anas done 👍