update EnumToString comment. Should we assert on an _Invalid value?

stepmania/src/EnumHelper.cpp

@@ -65,6 +65,9 @@ const RString &EnumToString( int iVal, int iMax, const char **szNameArray, auto_
 
 	// iMax+1 is "Invalid".  iMax+0 is the NUM_ size value, which can not be converted
 	// to a string.
+	// Maybe we should assert on _Invalid?  It seems better to make 
+	// the caller check that they're supplying a valid enum value instead of 
+	// returning an inconspicuous garbage value (empty string). -Chris
 	ASSERT_M( iVal >= 0 && (iVal < iMax || iVal == iMax+1), ssprintf("%i, %i, (%s)", iVal, iMax, szNameArray[0])  );
 	return *pNameCache[iVal];
 }