title: ERROR TypeError: data.map is not a function
body: <p>I get that error on my console, which I don't know how to fix</p>
  
  <p>ERROR TypeError: data.map is not a function</p>
  
  <pre><code>list(pageNumber: number = 1, pageSize: number = 10): Observable&lt;any[]&gt; {
          const params = new HttpParams()
            .set('pageNumber', `${pageNumber}`)
            .set('pageSize', `${pageSize}`);
  
          return this.api.get(this.apiController, { params })
            .pipe(map(data =&gt; data.map(item =&gt; {
              const picture = `${this.api.apiUrl}/${this.apiController}/${item.id}/photo`;
              return { ...item, picture };
            })));
        }
  </code></pre>