[haXe] Request: more descriptive exception when calling a null function reference

[Nicolas Cannasse]

> Hi Nicolas and List,
> 
> public static function main ():Void {
> 	var func:Bool -> Void = null;
> 	func(true);
> }
> 
> The above compiles successfully but throws the exception "Invalid
> call". Of course, in this case it is obvious why; the value of 'func'
> is null, and using null as a function pointer is not a good idea.
> 
> However, in the case that it is not immediately obvious to the
> programmer that the problem is caused by a null reference, the error
> message is not particularly helpful. Could the message possibly be
> changed to something a bit more descriptive, e.g. "Invalid call: null
> reference"?

This is not a good idea to print any value in exceptions, for security
reasons. Let's say that some users can figure out a way to make your
website raise this kind of exceptions, it could be used to display some
values (passwords) that should not be visible unless explicitly printed.

Nicolas