error NG1010: Value at position 0 in the NgModule.declarations of Module is not a reference

🐞 Bug report

If I do a postinstall ngcc I get the following errors in our library

Error: Failed to compile entry-point @syncfusion/ej2-angular-calendars (main as umd) due to compilation errors:
node_modules/@syncfusion/ej2-angular-calendars/dist/ej2-angular-calendars.umd.js:174:31 - error NG1010: Value at position 0 in the NgModule.declarations of CalendarModule is not a reference
  Value could not be determined statically.

174                 declarations: [
                                  ~
175                     exports.CalendarComponent
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
176                 ],
    ~~~~~~~~~~~~~~~~~

  node_modules/@syncfusion/ej2-angular-calendars/dist/ej2-angular-calendars.umd.js:175:21
    175                     exports.CalendarComponent
                            ~~~~~~~~~~~~~~~~~~~~~~~~~
    Unable to evaluate statically.
node_modules/@syncfusion/ej2-angular-calendars/dist/ej2-angular-calendars.umd.js:166:5 - error NG6002: Appears in the NgModule.imports of CalendarAllModule, but could not be resolved to an NgModule class.

Is it missing an @NgModule annotation?

166 var CalendarModule = /** @class */ (function () {
        ~~~~~~~~~~~~~~
node_modules/@syncfusion/ej2-angular-calendars/dist/ej2-angular-calendars.umd.js:166:5 - error NG6003: Appears in the NgModule.exports of CalendarAllModule, but could not be resolved to an NgModule, Component, Directive, or Pipe class.

Is it missing an Angular annotation?

Is this a regression?

Working fine with out "postinstall": "ngcc"

🔬 Minimal Reproduction

1. download my sample - https://github.com/kumaresan-subramani/Syncfusion-Calendar-Error-1

2. then give npm i or yarn i

My reported issue will occurs.

🔥 Exception or Error

🌍 Your Environment

    "@angular/animations": "~10.1.0",
    "@angular/common": "~10.1.0",
    "@angular/compiler": "~10.1.0",
    "@angular/core": "~10.1.0",
    "@angular/forms": "~10.1.0",
    "@angular/platform-browser": "~10.1.0",
    "@angular/platform-browser-dynamic": "~10.1.0",
    "@angular/router": "~10.1.0",
    "@angular-devkit/build-angular": "~0.1001.0",
    "@angular/cli": "~10.1.0",
    "@angular/compiler-cli": "~10.1.0",

Anything else relevant? I have done some researching and found that below issue and tried everything which are reported in those issues but no luck for me.

https://github.com/angular/angular/issues/35255#issuecomment-637055168 - downgraded ts version same error https://github.com/angular/angular/issues/36673#issuecomment-615140449 - tried changed my module declaration

This is our component config -

https://github.com/syncfusion/ej2-angular-ui-components/tree/master/components/calendars/src/calendar

Note: i am using ng-packagr to generate my angular library

[petebacondarwin]

I think the fixes appear in 10.1.6

[petebacondarwin]

Will do