Angular Type '{ }' is missing the following properties from type 'Blob': size, type, arrayBuffer, slice, and 2 more

I am creating a project in Angular that takes data from a GET call from an API, filters out specific data from the call, and writes it to a text file. I believe I am close on filtering out the data, but I am getting the error

Type '{ line1: any; line2: any; }' is missing the following properties from type 'Blob': size, type, arrayBuffer, slice, and 2 more.

Here is the typescript code where I am getting an error

const httpOptions = {
      headers: new HttpHeaders({
        'Content-Type':  'application/json',
        'Authorization': this.token
      })
    };
    this.http.get(this.url, httpOptions).subscribe((response) => {
      this.response = response;
      let line_1_2 = {line1:this.response.line1 , line2:this.response.line2};
      const blob = new Blob([line_1_2], { type: 'text/csv' });
      const url= window.URL.createObjectURL(blob);
      window.open(url);
    });

The line I am getting an error is:

const blob = new Blob([line_1_2], { type: 'text/csv' });

What do I need to do to make my object line_1_2 recognizable as a blob to print to a text file?