PostCSS could generate wrong source map error

[ionitron-bot]

Original issue by @mburger81 on 2018-01-04T15:59:56Z

Ionic version: (check one with "x")
(For Ionic 1.x issues, please use https://github.com/ionic-team/ionic-v1)
[ ] 2.x
[x] 3.x
[ ] 4.x

I'm submitting a ... (check one with "x")
[x] bug report
[ ] feature request

Please do not submit support requests or "How to" questions here. Instead, please use one of these channels: https://forum.ionicframework.com/ or http://ionicworldwide.herokuapp.com/

Current behavior:
If we build a new app using your blank starter or any other template building the android app we are running into this error

[16:52:18]  sass started ... 
Witout `from` option PostCSS could generate wrong source map or do not find Browserslist config. Set it to CSS file path or to `undefined` to prevent this warning
[16:52:19]  sass finished in 1.13 s 

Expected behavior:
The bug message should not be

Steps to reproduce:
Create a new blank app using
ionic start postcss
build the android app doing
ionic cordova build android

and you can see log with the warn or error message

[16:57:54]  sass started ... 
Witout `from` option PostCSS could generate wrong source map or do not find Browserslist config. Set it to CSS file path or to `undefined` to prevent this warning
[16:57:55]  sass finished in 793 ms 

Ionic info: (run ionic info from a terminal/cmd prompt and paste output below):

cli packages: (/usr/lib/node_modules)

    @ionic/cli-utils  : 1.19.0
    ionic (Ionic CLI) : 3.19.0

global packages:

    cordova (Cordova CLI) : 8.0.0 

local packages:

    @ionic/app-scripts : 3.1.6
    Cordova Platforms  : android 7.0.0
    Ionic Framework    : ionic-angular 3.9.2

System:

    Android SDK Tools : 26.1.1
    Node              : v8.9.4
    npm               : 5.6.0 
    OS                : Linux 4.13

Environment Variables:
    ANDROID_HOME : /abcdef/android/sdk

Misc:
    backend : legacy