title: Calling js method onCreateView failed System.err: TypeError: Right-hand side of 'instanceof' is not an object Nativescript
body: <p>I'm trying to use AppSync in my Nativescript application. This is the link I am following </p>
  
  <p><a href="https://market.nativescript.org/plugins/nativescript-app-sync" rel="nofollow noreferrer">https://market.nativescript.org/plugins/nativescript-app-sync</a></p>
  
  <p>Following this above link I have a code that checks whether the app is up to date or not</p>
  
  <p>Whenever I add this code</p>
  
  <pre><code>AppSync.sync({
      deploymentKey: isIOS ? "my-ios-deployment-key" : "my-android-deployment-key",
      installMode: InstallMode.ON_NEXT_RESUME, // this is the default install mode; the app updates upon the next cold boot (unless the --mandatory flag was specified while pushing the update)
      mandatoryInstallMode: isIOS ? InstallMode.ON_NEXT_RESUME : InstallMode.IMMEDIATE, // the default is InstallMode.ON_NEXT_RESUME which doesn't bother the user as long as the app is in the foreground. InstallMode.IMMEDIATE shows an installation prompt. Don't use that for iOS AppStore distributions because Apple doesn't want you to, but if you have an Enterprise-distributed app, go right ahead!
      updateDialog: { // only used for InstallMode.IMMEDIATE
          updateTitle: "Please restart the app", // an optional title shown in the update dialog
          optionalUpdateMessage: "Optional update msg",   // a message shown for non-"--mandatory" releases
          mandatoryUpdateMessage: "Mandatory update msg", // a message shown for "--mandatory" releases
          optionalIgnoreButtonLabel: "Later", // if a user wants to continue their session, the update will be installed on next resume
          mandatoryContinueButtonLabel: isIOS ? "Exit now" : "Restart now", // On Android we can kill and restart the app, but on iOS that's not possible so the user has to manually restart it. That's why we provide a different label in this example.
          appendReleaseDescription: true // appends the description you (optionally) provided when releasing a new version to AppSync
      } });
  </code></pre>
  
  <p>I always see this error</p>
  
  <pre><code>System.err: An uncaught Exception occurred on "main" thread.
  System.err: Calling js method onCreateView failed
  System.err: TypeError: Right-hand side of 'instanceof' is not an object
  System.err:
  System.err: StackTrace:
  System.err: (file: node_modules\@nativescript\core\ui\layouts\flexbox-layout\flexbox-layout.android.js:14:14)
  System.err:     at applyAllNativeSetters(file: node_modules\@nativescript\core\ui\core\properties\properties.js:1065:37)
  System.err:     at initNativeView(file: node_modules\@nativescript\core\ui\core\properties\properties.js:992:8)
  System.err:     at ViewBase.onResumeNativeUpdates(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:647:21)
  System.err:     at ViewBase._resumeNativeUpdates(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:278:17)
  System.err:     at ViewBase.onLoaded(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:232:13)
  System.err:     at View.onLoaded(file: node_modules\@nativescript\core\ui\core\view\view.android.js:249:34)
  System.err:     at (file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:317:89)
  System.err:     at ViewBase.callFunctionWithSuper(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:310:8)
  System.err:     at ViewBase.callLoaded(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:317:13)
  System.err:     at ViewBase.loadView(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:456:17)
  System.err:     at (file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:234:18)
  System.err:     at ContentView.eachChildView(file: node_modules\@nativescript\core\ui\content-view\content-view.js:70:12)
  System.err:     at PageBase.eachChildView(file: node_modules\@nativescript\core\ui\page\page-common.js:126:39)
  System.err:     at ViewCommon.eachChild(file: node_modules\@nativescript\core\ui\core\view\view-common.js:925:13)
  System.err:     at ViewBase.onLoaded(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:233:13)
  System.err:     at View.onLoaded(file: node_modules\@nativescript\core\ui\core\view\view.android.js:249:34)
  System.err:     at Page.onLoaded(file: node_modules\@nativescript\core\ui\page\page.android.js:43:34)
  System.err:     at (file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:317:89)
  System.err:     at ViewBase.callFunctionWithSuper(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:310:8)
  System.err:     at ViewBase.callLoaded(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:317:13)
  System.err:     at ViewBase.loadView(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:456:17)
  System.err:     at ViewBase._addViewCore(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:451:17)
  System.err:     at ViewBase._addView(file: node_modules\@nativescript\core\ui\core\view-base\view-base.js:437:13)
  System.err:     at FragmentCallbacksImplementation.onCreateView(file: node_modules\@nativescript\core\ui\frame\frame.android.js:700:18)
  System.err:     at FragmentClass.onCreateView(file: node_modules\@nativescript\core\ui\frame\fragment.android.js:29:37)
  System.err:     at com.tns.Runtime.callJSMethodNative(Native Method)
  System.err:     at com.tns.Runtime.dispatchCallJSMethodNative(Runtime.java:1286)
  System.err:     at com.tns.Runtime.callJSMethodImpl(Runtime.java:1173)
  System.err:     at com.tns.Runtime.callJSMethod(Runtime.java:1160)
  System.err:     at com.tns.Runtime.callJSMethod(Runtime.java:1138)
  System.err:     at com.tns.Runtime.callJSMethod(Runtime.java:1134)
  System.err:     at com.tns.FragmentClass.onCreateView(FragmentClass.java:53)
  System.err:     at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2439)
  System.err:     at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1460)
  System.err:     at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
  System.err:     at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
  System.err:     at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:802)
  System.err:     at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
  System.err:     at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
  System.err:     at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
  System.err:     at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273)
  System.err:     at androidx.fragment.app.FragmentManagerImpl$1.run(FragmentManager.java:733)
  System.err:     at android.os.Handler.handleCallback(Handler.java:751)
  System.err:     at android.os.Handler.dispatchMessage(Handler.java:95)
  System.err:     at android.os.Looper.loop(Looper.java:154)
  System.err:     at android.app.ActivityThread.main(ActivityThread.java:6119)
  System.err:     at java.lang.reflect.Method.invoke(Native Method)
  System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
  System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
  </code></pre>
  
  <p>But whenever the above line is commented out, the app runs perfectly fine</p>
  
  <p>What am I missing here</p>
  
  <p>Kindly help me out</p>
  
  <p>my package.json looks like this</p>
  
  <pre><code>"tns-ios": {
        "version": "6.5.0"
      },
      "tns-android": {
        "version": "6.5.0"
      }
    },
    "dependencies": {
      "@nativescript/theme": "~2.3.3",
      "nativescript-vue": "~2.5.0",
      "nativescript-webrtc-plugin": "^2.0.0-alpha.19",
      "nativescript-app-sync": "^2.0.0",
      "tns-core-modules": "~6.5.0",
      "@nstudio/nativescript-pulltorefresh": "^1.1.1",
      "axios": "^0.19.2",
      "country-code-info": "^0.3.0",
      "firebase": "^7.14.2",
      "firebase-admin": "^8.11.0",
      "libphonenumber-js": "^1.7.51",
      "mathjs": "^6.6.5",
      "nativescript-activity-detection": "^0.1.1",
      "nativescript-contacts-lite": "^0.2.6",
      "nativescript-exit": "^1.0.1",
      "nativescript-geolocation": "^5.1.0",
      "nativescript-headset-detection": "^1.0.0",
      "nativescript-local-notifications": "^4.2.1",
      "nativescript-permissions": "^1.3.9",
      "nativescript-plugin-firebase": "^10.5.2",
      "nativescript-social-share": "^1.6.0",
      "nativescript-socketio": "^3.3.1",
      "nativescript-toast": "^2.0.0",
      "vuex": "^3.3.0"
    },
    "devDependencies": {
      "@babel/core": "~7.1.0",
      "@babel/preset-env": "~7.1.0",
      "babel-loader": "~8.0.0",
      "nativescript-dev-webpack": "~1.5.1",
      "nativescript-vue-template-compiler": "~2.5.0",
      "node-sass": "^4.7.1",
      "@types/node": "^13.13.4",
      "dotenv": "^8.2.0",
      "nativescript-worker-loader": "^0.11.0",
      "tns-platform-declarations": "^6.5.1",
      "typescript": "^3.8.3",
      "vue": "^2.6.11",
      "vue-loader": "^15.9.2"
    },
    "prettier": {
      "trailingComma": "es5",
      "tabWidth": 2,
      "semi": false,
      "singleQuote": true,
      "bracketSpacing": true,
      "arrowParens": "avoid",
      "printWidth": 120
    }
  </code></pre>