I'm trying to complete the Handle Record Changes and Errors module but can't seem to get past the following challenge error:

Challenge Not yet complete... here's what's wrong: 
The 'accEdit' Lightning Component JS Controller does not appear to be setting 'v.recordSaveError' with an error message.

.I've tried many different combinations of sets and am not having much luck.

I've tried several different component.set methods such as this one:
component.set('v.recordSaveError','Error: ' + saveResult.state + ', message: ' + JSON.stringify(saveResult.error));

Any ideas what this module is looking for as a valid solution?

I do see recordSaveError display after being set due to an error.

Thanks.