Loading a saved Game

I have a script that saves certain variables to an .xml and then recalls them on load. When some plays for the first time they do not have this .xml file. If the player attempts to press the load button it throws an error saying it has not found the file. Once the player presses the save button then the game functions fine. I want to set an if statement to check if the file exists and if not then tell the player to save a file.The error is here:

 FileNotFoundException: Could not find file "/Users/ParkerCain/Desktop/Lucky Leprachaun/Assets/SaveData.xml".
 

all i need to do is check for it and if not there return null or something and give instruction. I don't know how to check for that however.

Here is my code:

 function LoadXML()
 {    
    var r : StreamReader = File.OpenText(_FileLocation+"/"+ _FileName);
    var _info : String = r.ReadToEnd();
    r.Close();
    _data=_info;
    Debug.Log("File Read");
 
 }

My assumption is that it should be something along the lines of :

 function LoadXML()
 {    
   if( //file is  found)
   {
    var r : StreamReader = File.OpenText(_FileLocation+"/"+ _FileName);
    var _info : String = r.ReadToEnd();
    r.Close();
    _data=_info;
    Debug.Log("File Read");
 }
   else()
     {
         Debug.Log("File not found");
     }
 }

Thanks for the help everyone.