This is what the debug console spits out for the response:
{
"error_code": 409,
"error": "username_exists",
"error_description": "There is already an account with this username"
}

This is what i get on my app console:
[ERROR] {
    "error_code" = 0;
    "error_description" = "(null)";
    source = "[object ti.geoloqi]";
    type = onFailure;
}