Handle a null answer from the server.

[sammyjava]

I'm finding that the server sometimes returns a null answer. This crashes the client app. This PR adds logic to spit out the response "I did not receive an answer!" when that happens. It isn't clear to me why the server returns a null answer rather than "I couldn't find the answer to that question in your files." It seems to vary with server restarts.

[sammyjava]

Good point. Actually, it should probably say that it received nothing, like "No response was returned." Agree? I'll update if so.

[simonpfish]

First and foremost, thank you for your interest in contributing to the cookbook and for the time you've invested in this pull request.

Unfortunately, due to current workload constraints and priorities, our team doesn't have the bandwidth to thoroughly review and integrate new pull requests for these full-stack examples. Please understand that this isn't a reflection on the quality of your work, which we genuinely appreciate. It's simply a matter of resource allocation and current focus.

Thank you again for your understanding and for your contribution.