Document can only be indexed into using square brackets or the index function

I am using square brackets but this error shows . 

what is wrong with my code?

  a!boxLayout(
    label: "Box",
    contents: {
      a!gridLayout(
        label: "Document",
        headerCells: {
          a!gridLayoutHeaderCell(label: "Document", align: "CENTER"),
          a!gridLayoutHeaderCell(label: "Name", align: "CENTER"),
          a!gridLayoutHeaderCell(label: "Classification", align: "CENTER"),
          a!gridLayoutHeaderCell(label: "Upload By", align: "CENTER"),
          a!gridLayoutHeaderCell(label: "Upload On", align: "CENTER")
        },
        columnConfigs: {
          a!gridLayoutColumnConfig(),
          a!gridLayoutColumnConfig(),
          a!gridLayoutColumnConfig(),
          a!gridLayoutColumnConfig(),
          a!gridLayoutColumnConfig()
        },
        rows: a!forEach(
          items: if(
            a!isNotNullOrEmpty(
              ri!record['recordType!{2206daff-ddbb-4759-a797-1588754c3925}SKJ Deposit Request.fields.{0cfaa083-3ffb-447a-b682-c5c16c88cd67}requestId']
            ),
            rule!SKJ_GetDoc(
              REQId:ri!record['recordType!{2206daff-ddbb-4759-a797-1588754c3925}SKJ Deposit Request.fields.{0cfaa083-3ffb-447a-b682-c5c16c88cd67}requestId']
            ).data,
            null
          ),
          expression: a!gridRowLayout(
            contents: {
              a!richTextDisplayField(
                value: a!richTextItem(
                  text: {
                    a!richTextIcon(icon: "download", color: "#0f203a"),
                    " ",
                    if(
                      a!isNotNullOrEmpty(
                        fv!item['recordType!{52d6bfd4-9a4e-457c-ab2e-ede6cffdb054}SKJ Document.fields.{6c686146-7506-45c1-b2e6-1db2e0eb6900}appianDocId']
                      ),
                      (
                        extract(
                          fn!getcontentobjectdetailsbyid(
                            fv!item['recordType!{52d6bfd4-9a4e-457c-ab2e-ede6cffdb054}SKJ Document.fields.{6c686146-7506-45c1-b2e6-1db2e0eb6900}appianDocId']
                          ),
                          "Name:",
                          ","
                        )
                      ),
                      null
                    )
                  },
                  link: a!documentDownloadLink(
                    document: fv!item['recordType!{52d6bfd4-9a4e-457c-ab2e-ede6cffdb054}SKJ Document.fields.{6c686146-7506-45c1-b2e6-1db2e0eb6900}appianDocId']
                  ),
                  linkStyle: "STANDALONE",
                  color: "#0f203a"
                ),
                align: "CENTER"
              ),
              a!textField(
                value: if(
                  a!isNotNullOrEmpty(
                    fv!item['recordType!{52d6bfd4-9a4e-457c-ab2e-ede6cffdb054}SKJ Document.fields.{6c686146-7506-45c1-b2e6-1db2e0eb6900}appianDocId']
                  ),
                  (
                    extract(
                      fn!getcontentobjectdetailsbyid(
                        fv!item['recordType!{52d6bfd4-9a4e-457c-ab2e-ede6cffdb054}SKJ Document.fields.{6c686146-7506-45c1-b2e6-1db2e0eb6900}appianDocId']
                      ),
                      "Name:",
                      ","
                    )
                  ),
                  null
                ),
                readOnly: true,
                align: "CENTER"
              ),
              a!textField(
                value:   fv!item['recordType!{52d6bfd4-9a4e-457c-ab2e-ede6cffdb054}SKJ Document.fields.{a3f411dd-394e-4039-a2d0-600d333f94b0}classification'],

                readOnly: true,
                align: "CENTER"
              ),
              a!textField(
                value: fv!item['recordType!{52d6bfd4-9a4e-457c-ab2e-ede6cffdb054}SKJ Document.fields.{66325d17-158b-4776-98b3-761a5a458e5c}addedBy'],
                readOnly: true,
                align: "CENTER"
              ),
              a!richTextDisplayField(
                label: "Uploaded On",
                labelPosition: "JUSTIFIED",
                value: fv!item['recordType!{52d6bfd4-9a4e-457c-ab2e-ede6cffdb054}SKJ Document.fields.{66325d17-158b-4776-98b3-761a5a458e5c}addedBy']
              )
            }
          )
        ),
        selectionSaveInto: {},
        validations: {},
        shadeAlternateRows: true,
        borderStyle: "LIGHT"
      )
      
    },
    style: "STANDARD",
    marginBelow: "STANDARD"
  )