I have a service call that makes a call to an API to return JSON. I then have a function with a subscribe that calls the service call. The JSOON is returned fine and the service call and subscribe all work. However, upon building my application in its build pipeline, I get the following error "Uncaught (in promise) TypeError: Cannot convert undefined or null to object." and my build fails (even though it works fine locally and passes all tests). I am using angular 9 and typescript.

My subscribe and the function that it's in look as such:

houseData: HouseValueObject;
houseNumber = '12345';

callHouseService() {
   this.streetHouseService.getHouseData(this.houseNumber).subscribe(
     async (data) => {
       this.houseData = await data;
       const keys = Object.keys(this.houseData.extensiveHouseData);
       this.extensiveHouseDataList = keys.map(k => this.houseData.extensiveHouseData[k]);
}
)
}

The getHouseData method looks as such:

export class HouseService {
  private readonly relativeURL = 'services/api/houseinfo/'
  
  constructor(private http: HttpClient) {
  
  getHouseData(houseNumber: string): Observable<HouseValueObject> {
   return.this.http.get<HouseValueObject>(this.relativeURL + houseNumber + '/');
}
}
}

The value object for HouseValueObject looks as such:

export class HouseValueObject {
   numberBathrooms: number;
   extensiveHouseData: HouseValue[];
}

I thought adding the async and await would suspend execution until the returned promise is fulfilled so that the JSON data would be delivered to const keys = Object.keys... line of code would work, but that does not appear to be the case. My question is, how can I correctly go about suspending execution until the returned promise is fulfilled to ensure the JSON data exists and the const keys = Object.keys... line of code works as it does locally?