Print diagnostic message if snapshot creation is not SUCCESS or ACCEPTED

[mrysav]

I have an Action that uses this library that is failing with an error message like this:

Error: Cannot read properties of null (reading 'toString')
Error: TypeError: Cannot read properties of null (reading 'toString')
    at /home/admin/actions-runner/_work/myrepo/myrepo/purl-submission-action/webpack:/purls-submission-action/node_modules/@github/dependency-submission-toolkit/dist/index.js:506:1
    at Generator.next (<anonymous>)
    at fulfilled (/home/admin/actions-runner/_work/myrepo/myrepo/purl-submission-action/webpack:/purls-submission-action/node_modules/@github/dependency-submission-toolkit/dist/index.js:395:1)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)

It seems that this section of code always assumes that there will be a createdAt value that is not null:

core.notice('Snapshot successfully created at ' + response.data.created_at.toString())

However, when I make a cURL request locally, I am getting a response with a null createdAt:

$ curl -u 'user:token' -H 'Content-Type: application/json' 'https://api.my-ghes-instance.com/repos/myuser/myrepo/dependency-graph/snapshots' -d @snap.json

{
  "id": 0,
  "created_at": null,
  "result": "REMOVED",
  "message": "The snapshot was valid, but not accepted. It did not apply to the default branch or was too historical to be considered applicable to the repository and was removed."
}

I figured out the reason for this response, but it would be better if this message was printed in the Action run. Additionally, the REMOVED result is not a documented return value, so that might be something we want to look into.