What steps does it take to reproduce the issue?
Call the MyData endpoint for a user that has no associated data. It should return successfully, with an empty list of items.
Instead, it returns an error response:
{"success":false,"error_message":"Sorry, no results were found."}
This makes it hard to distinguish between zero results, which is not an error, and other unexpected errors.

• What did you expect to happen?
  Return a normal response, with an empty list of items.
  For example,

{
    "success": true,
    "data": {
        "pagination": {
            "numResults": 0,
           . . . etc
        },
        "items": [],
        "total_count": 0,
        . . . etc
}

Which version of Dataverse are you using?
latest develop branch