Issue on the readonly grid when we pull data from Stored Procedure and display on screen

Geeting this error when used SP that returns datasubset for populating grid. Can someone provide more info on why this issue is coming up.

UI Code

a!localVariables(
  local!variableName,
  local!selectedSource,
  local!selectedCategory,
  local!pagingInfo:a!pagingInfo(
    startIndex: 1,
    batchSize: 10
  ),
  local!categories:index(rule!OMS_getPreSelectCategories(
    
  ),"data",{}),
  local!sources:index(rule!OMS_getPreSelectSourceTypes(
    
  ),"data",{}),
  local!mdmVariableList: a!refreshVariable(
    value: rule!OMS_SP_getPreSelectVarsByFilters(
      variableName: local!variableName,
      source: local!selectedSource,
      category: local!selectedCategory,
      pagingInfo: local!pagingInfo
    ),
    refreshOnVarChange: {
      local!variableName,
      local!selectedSource,
      local!selectedCategory
    }
  ),
  a!cardLayout(
    style: "TRANSPARENT",
    contents: {
      a!columnsLayout(
        columns: {
          a!columnLayout(
            contents: a!richTextDisplayField(
              value: a!richTextItem(
                text: "Add More Variables to Set " & ri!sequenceNumber,
                style: "STRONG",
                size: "MEDIUM"
              )
            )
          ),
          a!columnLayout(
            contents: a!buttonLayout(
              primaryButtons: a!buttonWidget(
                label: "CANCEL",
                color: "NEGATIVE",
                saveInto: a!save(ri!hideVariableGrid[ri!currentSetNumber], true())
              )
            )
          )
        },
        marginBelow: "EVEN_LESS"
      ),
      a!columnsLayout(
        columns: {
          a!columnLayout(
            a!textField(
              placeholder: "Search",
              value: local!variableName,
              saveInto: local!variableName
            )
          ),
          a!columnLayout(
            a!dropdownField(
              placeholder: "Filter By Category",
              choiceLabels: index(local!categories,"masterAcaFileFieldGroupName",{}),
              choiceValues: index(local!categories,"masterAcaFileFieldGroupName",{}),
              value:local!selectedCategory,
              saveInto: local!selectedCategory
            ),
          ),
          a!columnLayout(
            a!dropdownField(
              placeholder: "Filter By Source",
              choiceLabels:index(local!sources,"source",{}) ,
              choiceValues: index(local!sources,"source",{}),
              value:local!selectedSource,
              saveInto: local!selectedSource
            )
          ),
          a!columnLayout(
            /*a!dropdownField(*/
              /*placeholder: "Filter By Profiled",*/
              /*choiceLabels: {"Yes","No"},*/
              /*choiceValues: {"Yes","No"},*/
              /*value:local!selectedProfiled,*/
              /*saveInto: local!selectedProfiled*/
            /*)*/
          )
        }
      ),
      a!gridField(
        labelPosition: "ABOVE",
        data:local!mdmVariableList,
        pagingSaveInto: local!pagingInfo,
        columns: {
          a!gridColumn(
            label: "Variables",
            value: fv!row.VAR_NAME,
            width: "MEDIUM"
          ),
          a!gridColumn(
            label: "Description",
            value: fv!row.DESCRIPTION,
            width: "MEDIUM"
          ),
          a!gridColumn(
            label: "Category", 
            width: "NARROW_PLUS",
            value:fv!row.MASTER_ACA_FILE_FIELD_GROUP_NAME
          ),
          /*a!gridColumn(label: "Profiled", width: "NARROW_PLUS"),*/
          a!gridColumn(
            label: "Variable Source",
            width: "NARROW_PLUS",
            value:fv!row.SOURCE
          ),
          a!gridColumn(
            label: "Add",
            value: a!buttonLayout(
              primaryButtons: a!buttonWidget(
                icon: "plus-circle",
                label: "ADD",
                saveInto: {
                  a!save(
                    ri!omsJobPreSelectionAndFilter,
                    append(
                      ri!omsJobPreSelectionAndFilter,
                      'type!{urn:com:appian:types:OMS}OMS_JOB_PRESELECTION_AND_FILTER'(
                        omsJobId: ri!omsJobId,
                        preselectionSetId: ri!sequenceNumber,
                        preselectionFilterId: if(
                          a!isNullOrEmpty(ri!omsJobPreSelectionAndFilter),
                          1,
                          count(ri!omsJobPreSelectionAndFilter) + 1
                        ),
                        mdmVariableId: fv!row.MDM_VARIABLES_ID,
                        preselectionFilterOperationId: null,
                        dltdInd: false(),
                        creatUsrTxt: loggedInUser(),
                        creatTs: now(),
                        lastUpdtUsrTxt: loggedInUser(),
                        lastUpdtTs: now()
                      )
                    )
                  )
                }
              )
            ),
            width: "ICON_PLUS"
          )
        },
        validations: {}
      )
    },
    showShadow: true(),
    showWhen: not(
      a!defaultValue(ri!hideVariableGrid[ri!currentSetNumber], "false")
    )
  )
)

SP Rule Code - this returns a datasubset

a!localVariables(
  local!storedProcResults: a!executeStoredProcedureForQuery(
    dataSource: "jdbc/AlliantOMS",
    procedureName: "GET_PRESELECT_VARS",
    inputs: {
      a!storedProcedureInput(
        name: "startIndex",
        value: ri!pagingInfo.startIndex
      ),
      a!storedProcedureInput(
        name: "batchSize",
        value: ri!pagingInfo.batchSize
      ),
      a!storedProcedureInput(name: "varName", value: ri!variableName),
      a!storedProcedureInput(name: "category", value: ri!category),
      a!storedProcedureInput(name: "source", value: ri!source),
      a!storedProcedureInput(name: "profiled", value: ri!profiled)
    }
  ),
  local!totalCount: local!storedProcResults.results[2].cnt,
  a!dataSubset(
    startIndex: ri!pagingInfo.startIndex,
    batchSize: ri!pagingInfo.batchSize,
    totalCount: local!totalCount,
    data:local!storedProcResults.results[1],
    identifiers: toString(
      index(
        local!storedProcResults.results[1],
        "MDM_VARIABLES_ID",
        ""
      )
    )
  )
)

Sample SP Result Set Row with pagingdata

'type!{http://www.appian.com/ae/types/2009}DataSubset'('startIndex': 1, 'batchSize': 1, 'sort': {null}, 'totalCount': 28423, 'data': {a!map(MDM_VARIABLES_ID: 907941.0, SYSTM_CD: "5CBA1BC6-BD4E-DE0C-8F5E-6CABE78C6578", SDESC: "ACCOUNT_CODE_1", LDESC: "", VAR_NAME: "ACCOUNT_CODE_1_NICK", VARIABLE_USED_IND: "False", CONTRIB_SPECIFIC_VARIABLE_IND: "False", CONTRIBUTOR_ID: "", LEVEL_ID: "PLK", VARIABLE_GROUP_ID: null, DESCRIPTION: "DESCRIPTION_TEST", LONG_DESCRIPTION: "", IS_MODEL_DEV_VAR_IND: "False", IN_ALL_MODEL_DEV_MATCHES_IND: "False", USED_IN_MODEL_DEV_IND: "False", MODEL_DEV_MATCH_FLAG_ID: null, ALLOWED_AS_PREDICTOR_IND: "False", USED_IN_MODELS_TRANSFORMS_IND: "False", TOTAL_TRANSFORMS_COUNT: "0", IS_USED_IN_REAL_TIME_IND: "False", USED_IN_LICENSED_INSTALL_IND: "False", USED_IN_DIGITAL_SUPERSET_IND: "False", IS_USED_IN_APPLAUD_IND: "", IS_CCPA_AWARE_VAR_ID: "YES", MARKET_CREDIT_AWARE_VAR_ID: "NO", FLA_COMPLIANT_IND: "", FHA_COMPLIANT_IND: "", FCRA_COMPLIANT_IND: "", SNSTV_PI_ADJUSTMENT_IND: "True", SNSTV_HEALTH_ADJUSTMENT_IND: "", THIRD_PARTY_DATA_SOURCE: "Data Axle Demo", FOR_ENRCHMNT_USE_IND: "", SOURCE_FILE: "infogroup_plk_variables", JAR_NAME: "/ there is somethign here", DATA_TYPE_ID: null, EXPRESSION: "0", COMMON_VAR_NAME_ID: "", NUMERATOR_VAR_NAME_ID: "", DENOMINATOR_VAR_NAME_ID: "", LTST_MGRTD_MDL_NM_ID: "", LATEST_RUN_MODEL_NAME: "", LATEST_RUN_MODEL_RUN_DATE: "", AVLBL_FOR_PRE_SLCT_IND: "", REGEX_VLDTN: null, MASTER_ACA_FILE_FIELD_GROUP_NAME: null, SOURCE: "MODEL")}, 'identifiers': {"907941"})