Build Prod failed. Could not find cordova.js script tag. Plugin loading may fail

Could anyone suggest please, what is going wrong ? When I am running ionic cordova build ios --prod

I see white screen with errors…

TypeError: undefined is not a constructor (evaluating ‘new o.BehaviorSubject(!1)’)

Could not find cordova.js script tag. Plugin loading may fail.

But if I am running

ionic cordova build ios … everything is ok.

Ionic info:

Ionic:

Ionic CLI : 6.12.4 (/usr/local/lib/node_modules/@ionic/cli)
Ionic Framework : @ionic/angular 5.5.2
@angular-devkit/build-angular : 0.1000.8
@angular-devkit/schematics : 10.0.8
@angular/cli : 10.0.8
@ionic/angular-toolkit : 2.3.3

Cordova:

Cordova CLI : 10.0.0
Cordova Platforms : none
Cordova Plugins : no whitelisted plugins (0 plugins total)

Utility:

cordova-res : not installed
native-run : not installed

System:

ios-deploy : 1.11.3
ios-sim : 8.0.2
NodeJS : v14.15.4 (/usr/local/bin/node)
npm : 6.14.10
OS : macOS Big Sur
Xcode : Xcode 12.4 Build version 12D4e

problem solved. Change import { BehaviorSubject } from ‘rxjs’;