I'm using a child component:

<app-photo-editor [addPhotoUrlExtension]="'users/add-photo'" [onUploadSuccess]="onUploadPhotoSuccess"
                [deletePhoto]="onDeletePhoto"></app-photo-editor>  

and passing it the onUploadPhotoSuccess function:

 onUploadPhotoSuccess(response: any) {
    if (response) {
      const photo = JSON.parse(response);
      this.member.photoUrl = photo.url;  // offending line
      ...

On the child component, I accept the function, and invoke the parent's function:

export class PhotoEditorComponent implements OnInit {
  @Input() onUploadSuccess: (response: any) => void;

...

this.uploader.onSuccessItem = (item, response, status, headers) => {
      if (response) {
        this.onUploadSuccess(response);
      }
    }  

This gives an error on the offending line (marked above), saying:

core.js:6498 ERROR TypeError: Cannot set properties of undefined (setting 'photoUrl')
    at PhotoEditorComponent.onUploadPhotoSuccess [as onUploadSuccess] (member-edit.component.ts:67:27)
    at FileUploader.uploader.onSuccessItem (photo-editor.component.ts:60:14)
    at FileUploader._onSuccessItem (ng2-file-upload.js:1326:1)
    at XMLHttpRequest.xhr.onload [as __zone_symbol__ON_PROPERTYload] (ng2-file-upload.js:1073:29)
    at XMLHttpRequest.wrapFn (zone.js:763:1)
    at ZoneDelegate.invokeTask (zone.js:406:1)
    at Object.onInvokeTask (core.js:28679:1)
    at ZoneDelegate.invokeTask (zone.js:405:1)
    at Zone.runTask (zone.js:178:1)
    at ZoneTask.invokeTask [as invoke] (zone.js:487:1)  

Which means this.member is undefined, now on one hand it does makes sense I would have needed to pass it to the child component, but on the other, I THINK this worked as is.. So I'm not sure what's the right solution..