How to resolve "Invalid index: Cannot index property 'employee' of type Text into null value of type list" this error?

You get this error when you try to use the dot-notation to access a field in a data structure. But I do not see that in your code snippet.

BTW, what is line 27 meant to do?

BBTW, nested CDTs are not recommended.

If I without use typeof then also same error occurred. So how to resolve it. Please suggest.

local!supervisorList: if(
    contains({ 3, 6 }, ri!selectedDashboard),
    index(
      /*a!isNotNullOrEmpty(tointeger(ri!reportingEmployeeList)),*/
      ri!reportingEmployeeList,
      wherecontains(
        cons!INO_DESIG_ID_SUPERVISOR,
        tointeger(
          index(
            ri!reportingEmployeeList,
            "designationId",
            0
          )
        )
      ),
      {}
    ),
    null
  ),
  local!supervisorHierarchyList: if(
    contains({ 3, 6 }, ri!selectedDashboard),
    a!forEach(
      items: local!supervisorList,
      expression: 'type!{urn:com:appian:types:INO}INO_employeeHierarchyHelper'(
        employee: fv!item,
        directReportEmployeeList: index(
          ri!reportingEmployeeList,
          wherecontains(
            index(local!supervisorList, "internalEmpId"),
            tointeger(
              index(
                ri!reportingEmployeeList,
                "currentReportingManagerId",
                0
              )
            )
          ),
          {}
        )
        /*index(
          local!supervisorList,
          wherecontains(
            /*fv!item.internalEmpId,*/
            /*index(ri!reportingEmployeeList, "internalEmpId"),
            tointeger(
              index(
                ri!reportingEmployeeList,
                "currentReportingManagerId",
                0
              )
            )
          ),
          {}
        )*/
      )
    ),
    null
  ),

If I without use typeof then also same error occurred. So how to resolve it. Please suggest.

local!supervisorList: if(
    contains({ 3, 6 }, ri!selectedDashboard),
    index(
      /*a!isNotNullOrEmpty(tointeger(ri!reportingEmployeeList)),*/
      ri!reportingEmployeeList,
      wherecontains(
        cons!INO_DESIG_ID_SUPERVISOR,
        tointeger(
          index(
            ri!reportingEmployeeList,
            "designationId",
            0
          )
        )
      ),
      {}
    ),
    null
  ),
  local!supervisorHierarchyList: if(
    contains({ 3, 6 }, ri!selectedDashboard),
    a!forEach(
      items: local!supervisorList,
      expression: 'type!{urn:com:appian:types:INO}INO_employeeHierarchyHelper'(
        employee: fv!item,
        directReportEmployeeList: index(
          ri!reportingEmployeeList,
          wherecontains(
            index(local!supervisorList, "internalEmpId"),
            tointeger(
              index(
                ri!reportingEmployeeList,
                "currentReportingManagerId",
                0
              )
            )
          ),
          {}
        )
        /*index(
          local!supervisorList,
          wherecontains(
            /*fv!item.internalEmpId,*/
            /*index(ri!reportingEmployeeList, "internalEmpId"),
            tointeger(
              index(
                ri!reportingEmployeeList,
                "currentReportingManagerId",
                0
              )
            )
          ),
          {}
        )*/
      )
    ),
    null
  ),

Hm ....

What I mean is that

typeof(ri!reportingEmployeeList),

returns the ID of the data type of that rule input. Trying to index() into this makes no sense for me. Help me understand what you are trying to do.