this.emitter = fromEventPattern(this.addHandler, this.removeHandler, (err, char) => [err, char]); <= unchanged
this.rxSubscription = this.rxSubscription = this.emitter.concatMap(value:any => this.handleUpdatedValuesComingFromSensor(value)).subscribe(); <= concatMap does not exist on type Observable<any>

handleUpdatedValuesComingFromSensor = async (arr: any[]): Promise<void> => {
   ...
   await someMethodAsync();
   ...
}