[BitBucket user: Sébastien Jodogne]
[BitBucket date: 2019-01-25.12:15:57]

This issue was essentially a missing description of the error message. This is now fixed:

```text
# Test with a invalid Orthanc identifier (results in a 400 error without body in Orthanc <= 1.5.2):
$ curl http://localhost:8042/modalities/self/store -X POST -d '["19816330-cb02e1cf-df3a8fe8-bf510623-ccefe9f"]' -i
HTTP/1.1 400 Bad Request
Connection: keep-alive
Content-Length: 324

{
   "Details" : "This string is not a valid Orthanc identifier: 19816330-cb02e1cf-df3a8fe8-bf510623-ccefe9f",
   "HttpError" : "Bad Request",
   "HttpStatus" : 400,
   "Message" : "Bad file format",
   "Method" : "POST",
   "OrthancError" : "Bad file format",
   "OrthancStatus" : 15,
   "Uri" : "/modalities/self/store"
}

# Test with a valid Orthanc identifier, but nonexistent DICOM instance:
$ curl http://localhost:8042/modalities/self/store -X POST -d '["19816330-cb02e1cf-df3a8fe8-bf510623-ccefe9f6"]' -i
HTTP/1.1 404 Not Found
Connection: keep-alive
Content-Length: 215

{
   "HttpError" : "Not Found",
   "HttpStatus" : 404,
   "Message" : "Unknown resource",
   "Method" : "POST",
   "OrthancError" : "Unknown resource",
   "OrthancStatus" : 17,
   "Uri" : "/modalities/self/store"
}
```