Code review comment for lp:~nbrinza/zorba/bugs2

The TRY_XS_INT_CONVERT should probably be more like:

 #define TRY_XS_INT_CONVERT(target, value, xs_type) \
   { \
     XS_TYPE const res( value ); \
     try { \
       target = to_xs_int(res); \
     } catch (std::range_error const&) { \
       throw XQUERY_EXCEPTION(err::FODT0002, ERROR_PARAMS(res.toString())); \
     } \
   }