How To Put XMLTextReader Cursor Back To Start

I've got a function api_request which takes API method as an argument, and returns XMLTextReader.
Shared Function api_request(method As String) As XmlTextReader
request_text = method & ".xml"
url = "[URL]" & request_text & "&access_token=" & token
Return New XmlTextReader(url)
End Function

I call this function from different places to make request to site API and depending on the method results are parsed very differently. So in each method I have something like this:
Dim s As Xml.XmlReader = api_request("users.get")
While s.Read
If s.NodeType = XmlNodeType.Element Then
If s.Name = "user" Then
[Code] .....

As you may see, I have the code ElseIf s.Name = "error" Then error_handler(s, "user.get"). This is because when error happens, server always returns something like this:
<error>
<error_code>4</error_code>
<error_msg>Incorrect signature</error_msg>
</error>

This is parsed in error_handler Sub, and depending on the error following actions are chosen. This code works, but I have to check if I encounter error like that ElseIf s.Name = "error" every time, though all the methods call the api_request function. Is it possible to check for error in api_request function before returning the Reader? The problem is if I start reading xml there, and there isn't an error, I can't anyhow position the Reader to the start.