= load(
  with(
    local!matches: where(
      apply(
        search(
          ri!filter,
          _
        ),
        ri!labels
      )
    ),
    if(
      (
        /* no values found */
        length(
          local!matches
        ) = 0
      ),
	  /* ADDED THE CASE OF NOT FOUND */
      'type!{http://www.appian.com/ae/types/2009}DataSubset'(
        data: {
          "RESULT NOT FOUND"
        },
        identifiers: {
		 -1 
		 /* should be better define here a constant like the following:
          *  cons!valueFor_RESULT_NOT_FOUND
		  */
        }
      ),
      'type!{http://www.appian.com/ae/types/2009}DataSubset'(
        data: index(
          ri!labels,
          local!matches
        ),
        identifiers: index(
          ri!identifiers,
          local!matches
        )
      )
    )
  )
)