app.component.html

<StackLayout>
    <Label [text]="appVersion"></Label>
</StackLayout>

app.component.ts

import {Component, OnInit} from "@angular/core";
let appversion = require("nativescript-appversion");

@Component({
    selector: "my-app",
    templateUrl: "app.component.html",
})
export class AppComponent implements OnInit {

    appVersion: string;

    constructor() {
    }

    public ngOnInit() {
        appversion.getVersionName().then((v: string) => {
          console.log("Your app's version is: " + v);
          this.appVersion = v;
        });
    }
}

error.txt

JS: Your app's version is: 1.0

JS: EXCEPTION: Uncaught (in promise): TypeError: Cannot set property 'appVersion' of null
JS: ORIGINAL STACKTRACE:
JS: Error: Uncaught (in promise): TypeError: Cannot set property 'appVersion' of null
JS:     at resolvePromise (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:416:31)
JS:     at /data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:452:17
JS:     at ZoneDelegate.invokeTask (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:223:37)
JS:     at Object.onInvokeTask (/data/data/org.nativescript.temp/files/app/tns_modules/@angular/core/bundles/core.umd.js:4396:41)
JS:     at ZoneDelegate.invokeTask (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:222:42)
JS:     at Zone.runTask (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:123:47)
JS:     at drainMicroTaskQueue (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:355:35)
JS: Unhandled Promise rejection: Cannot set property 'appVersion' of null ; Zone: angular ; Task: Promise.then ; Value: TypeError: Cannot set property 'appVersion' of null TypeError: Cannot set property 'appVersion' of null
JS:     at /data/data/org.nativescript.temp/files/app/app.component.js:10:29
JS:     at ZoneDelegate.invoke (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:190:28)
JS:     at Object.onInvoke (/data/data/org.nativescript.temp/files/app/tns_modules/@angular/core/bundles/core.umd.js:4405:41)
JS:     at ZoneDelegate.invoke (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:189:34)
JS:     at Zone.run (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:83:43)
JS:     at /data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:449:57
JS:     at ZoneDelegate.invokeTask (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:223:37)
JS:     at Object.onInvokeTask (/data/data/org.nativescript.temp/files/app/tns_modules/@angular/core/bundles/core.umd.js:4396:41)
JS:     at ZoneDelegate.invokeTask (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:222:42)
JS:     at Zone.runTask (/data/data/org.nativescript.temp/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:123:47)
JS: Error: Uncaught (in promise): TypeError: Cannot set property 'appVersion' of null