Ngui Tab error... anyone?

Hello Ionic users,

I’m using an npm component called ngui Tab which is just a normal javascript tab.
I found it working in Ionic pretty well.

It works fine when I build an apk file uisng
ionic cordova build android --release

However it doesn’t work when I try to build an apk using:
ionic cordova build android --release --prod

It gives me this error:

Error: Unexpected value 'NguiTabModule in C:/Users/MyLaptop/demo-app/node_modules/@ngui/tab/dist/tab.module.d.ts' imported by the module 'AppModule in C:/Users/MyLaptop/demo-app/src/app/app.module.ts'. Please add a @NgModule annotation.
    at Error (native)
    at syntaxError (C:\Users\MyLaptop\demo-app\node_modules\@angular\compiler\bundles\compiler.umd.js:1729:34)
    at C:\Users\MyLaptop\demo-app\node_modules\@angular\compiler\bundles\compiler.umd.js:15577:44
    at Array.forEach (native)
    at CompileMetadataResolver.getNgModuleMetadata (C:\Users\MyLaptop\demo-app\node_modules\@angular\compiler\bundles\compiler.umd.js:15560:49)
    at addNgModule (C:\Users\MyLaptop\demo-app\node_modules\@angular\compiler\bundles\compiler.umd.js:24403:58)
    at C:\Users\MyLaptop\demo-app\node_modules\@angular\compiler\bundles\compiler.umd.js:24414:14
    at Array.forEach (native)
    at _createNgModules (C:\Users\MyLaptop\demo-app\node_modules\@angular\compiler\bundles\compiler.umd.js:24413:26)
    at analyzeNgModules (C:\Users\MyLaptop\demo-app\node_modules\@angular\compiler\bundles\compiler.umd.js:24288:14)

Why does this happen?
It looks like it’s because this Ngui npm module is not really an original angular or ionic module?

When I remove NguiTabModule from app.module.ts and imports, I can bypass that error and build an apk file using --release --prod command.
However then my app is forever stuck on loading screen…
I need some help.