Fix error on conference join when calendar is disabled

react/features/calendar-sync/components/ConferenceNotification.native.js

 import { getLocalizedDateFormatter, translate } from '../../base/i18n';
 import { ASPECT_RATIO_NARROW } from '../../base/responsive-ui';
 
+import { CALENDAR_ENABLED } from '../constants';
 import styles from './styles';
 
 const ALERT_MILLISECONDS = 5 * 60 * 1000;
     };
 }
 
-export default translate(connect(_mapStateToProps)(ConferenceNotification));
+export default CALENDAR_ENABLED
+    ? translate(connect(_mapStateToProps)(ConferenceNotification))
+    : undefined;

react/features/conference/components/Conference.native.js

                 </View>
                 <TestConnectionInfo />
 
-                <ConferenceNotification />
+                {
+                    this._renderConferenceNotification()
+                }
 
                 {/*
                   * The dialogs are in the topmost stacking layers.
         return this._backHandler && this.props._onHardwareBackPress();
     }
 
+    /**
+     * Renders the conference notification badge if the feature is enabled.
+     *
+     * Note: If the calendar feature is disabled on a platform, then we don't
+     * have its components exported so an undefined check is necessary.
+     *
+     * @private
+     * @returns {React$Node}
+     */
+    _renderConferenceNotification() {
+        return ConferenceNotification
+            ? <ConferenceNotification />
+            : undefined;
+    }
+
     /**
      * Triggers the default Toolbox timeout.
      *