Microsoft.JScript Compilation Errors

I am trying to use a Script to evaluate custom functions

Script.js

interface ICustomClass
{
function get ConvertFloatToHex(floatValue : float) : String;
}

class CustomScriptEvaluator
{
static var CustomClass : ICustomClass;

function CustomScriptEvaluator(CustomClass : ICustomClass)
{
CustomScriptEvaluator.CustomClass = CustomClass;
}
static function Evaluate(expression : String) : String
{
return eval(expression);
}
}

I use the jsc command to get the Script.dll from the Script.js file.
Implementing the interface ICustomClass

CustomClass.cs

public class CustomClass : ICustomClass
{
public string ConvertFloatToHex(float floatValue)
{
const string hex="0";
return (hex + "h");
}
}

ScriptEvaluator.cs


public ScriptEvaluator
{
//Private Member declaration...

public static ScriptEvaluator Instance
{
get
{
if(m_instance==null)
{
m_instance = new ScriptEvaluator(ICustomClass customClass);
}
return m_instance;
}
}
private ScriptEvaluator(ICustomClass customClass)
{
CustomClass = customClass;
var instancing = new CustomScriptEvaluator(CustomClass);
}
public string Evaluate(String script)
{
return CustomScriptEvaluator.Evaluate(script);
}
}

When I am using something like:

var result = ScriptEvaluator.Instance.Evaluate("CustomClass.ConvertFloatToHex(2.5,26,12)=='0h' ");

That sentence executes correctly, no matter that the number of parameters is **wrong**. So, I would like it to send an excepcion when this happens.

Is there a way to do that?

Thanks in advance.