Unkonwn error after building IOS

I integrated Themeablebrowser in my ionic application . But currently it dosent work on some of my ios devices . crashing by throwing this error :

`2017-11-13 17:33:45.052 Toufoula Kids[231:20451] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString charValue]: unrecognized selector sent to instance 0x19164a20'
*** First throw call stack:
(0x2470791b 0x23ea2e17 0x2470d2b5 0x2470aee1 0x24636238 0x24ec40f3 0x24e7b33d 0x24e7b1f3 0x8f937 0x8fac9 0x8f317 0xbc869 0x691d9 0x6902b 0x6a913 0x2b6796a1 0x2b629487 0x2b62ac53 0x2b62ab4f 0x2b62aaeb 0x2b4e3bf9 0x2b6126bf 0x2b4af58b 0x2b4b0f9b 0x27b6bb65 0x27b6bebb 0x246c9dff 0x246c99ed 0x246c7d5b 0x24617229 0x24617015 0x25c07ac9 0x28ceb189 0x32d03 0x242bf873)
libc++abi.dylib: terminating with uncaught exception of type NSException

And this is my home.ts file

 const options: ThemeableBrowserOptions = {

          toolbar: {
              height: 38,
              color: 'rgba(255, 255, 255, .4);'
          },
        closeButton: {

            wwwImage: 'assets/img/btn_back1.png',
            wwwImagePressed: 'assets/img/btn_back1.png',
            wwwImageDensity: 2,
            align: 'left',
            event: 'closePressed'
          },
          fullscreen : 'true',
           backButtonCanClose: true
     };

 const browser: ThemeableBrowserObject = this.themeableBrowser.create(url, '_blank', options);

            browser.on("closePressed") .subscribe(  res => {
                browser.close();
                 this.fn();
               },
               err => {
                 console.log("InAppBrowser Loadstop Event Error: " + err);
  });

package file

` "dependencies": {
    "@angular/common": "^5.0.0",
    "@angular/compiler": "5.0.0",
    "@angular/compiler-cli": "5.0.0",
    "@angular/core": "5.0.0",
    "@angular/forms": "5.0.0",
    "@angular/http": "5.0.0",
    "@angular/platform-browser": "5.0.0",
    "@angular/platform-browser-dynamic": "5.0.0",
    "@ionic-native/camera": "4.3.3",
    "@ionic-native/core": "4.3.3",
    "@ionic-native/file": "^4.4.0",
    "@ionic-native/file-transfer": "^4.4.0",
    "@ionic-native/firebase": "^4.4.0",
    "@ionic-native/google-analytics": "^4.4.0",
    "@ionic-native/in-app-browser": "^4.4.0",
    "@ionic-native/native-storage": "^4.4.0",
    "@ionic-native/screen-orientation": "^4.4.0",
    "@ionic-native/splash-screen": "4.3.3",
    "@ionic-native/status-bar": "4.3.3",
    "@ionic-native/themeable-browser": "^4.4.0",
    "@ionic-native/transfer": "^3.14.0",
    "@ionic-native/youtube-video-player": "^4.4.0",
    "@ionic/storage": "2.1.3",
    "@ngx-translate/core": "8.0.0",
    "@ngx-translate/http-loader": "^2.0.0",
    "angularfire2": "^4.0.0-rc.0",
    "firebase": "^3.9.*",
    "ionic-angular": "3.9.2",
    "ionicons": "3.0.0",
    "rxjs": "5.5.2",
    "sw-toolbox": "3.6.0",
    "zone.js": "0.8.18"
  },
  "devDependencies": {
    "@ionic/app-scripts": "3.1.0",
    "typescript": "2.4.2"
  },
  "description": "An Ionic project"
}`

I would be so happy to get help and the plugin working as soon as possible

initialxy / cordova-plugin-themeablebrowser

Unkonwn error after building IOS #165