Ionic 4 upgrade File to import not found or unreadable: ionic.globals

I am trying to upgrade ionic 2 app to Ionic 4, stuck at the an issue

Update:

I have manually imported the theme files scss from node_modules folder but still my sidemenu from Ionic 2 looks distorted and theme cannot be imported or side menu, is there a guide on how to properly upgrade Ionic 2 sidemenu app to Ionic 4 with same theme?

Original Post

ERROR in ./src/theme/variables.scss (./node_modules/@angular-devkit/build-angular/src/angular-cli-files/plugins/raw-css-loader.js!./node_modules/postcss-loader/src??embedded!./node_modules/sass-loader/lib/loader.js??ref–14-3!./src/theme/variables.scss)
Module build failed (from ./node_modules/sass-loader/lib/loader.js):

undefined
^
File to import not found or unreadable: ionic.globals.
in xxxxx\src\theme\variables.scss (line 22, column 1)
ERROR in ./src/global.scss (./node_modules/@angular-devkit/build-angular/src/angular-cli-files/plugins/raw-css-loader.js!./node_modules/postcss-loader/src??embedded!./node_modules/sass-loader/lib/loader.js??ref–14-3!./src/global.scss)
Module build failed (from ./node_modules/sass-loader/lib/loader.js):

undefined
^
File to import not found or unreadable: ~@ionic/angular/themes/ionic.globals.scss

Any help would be appreciated
Thanks