Creating test with empty domain gives confusing error message

[matsduf]

An empty domain is not allowed and should not be allowed, but it would be good if the error message says that the domain name must not be empty, not giving an incorrect message that the characters are not supported.

{
  "jsonrpc": "2.0",
  "id": 1,
  "params": {
    "domain": ""
  },
  "method": "start_domain_test"
}
{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "data": [
      {
        "path": "/domain",
        "message": "The domain name character(s) are not supported"
      }
    ],
    "message": "Invalid method parameter(s).",
    "code": "-32602"
  }
}

Here is a correct example of a domain with a character not supported, and the error message is the same:

{
  "jsonrpc": "2.0",
  "id": 1,
  "params": {
    "domain": "zonemaster:net"
  },
  "method": "start_domain_test"
}
{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "data": [
      {
        "path": "/domain",
        "message": "The domain name character(s) are not supported"
      }
    ],
    "message": "Invalid method parameter(s).",
    "code": "-32602"
  }
}