Downloading a package that is missing against a virtual repository can cause a NPE

Steps to reproduce:

1. Create a local repository
2. Create a virtual repository that aggregated the local repository.
3. Run the following command:

curl http://localhost:9091/artifactory/api/nuget/nuget-virtual/Download/TFSDataService/1.0.17.0

Since the package is not in the local, NPE is throwing in the logs:
2018-02-14 10:12:01,210 [http-nio-9091-exec-15] ERROR o.a.r.c.e.GlobalExceptionMapper:48 - null

And the command respond is:

{
  "errors" : [ {
    "status" : 500,
    "message" : "An unexpected error has occurred, please check Artifactory logs for further details."
  } ]
}