Write to data store using forEach

Hello, I'm trying to write an array of data using foreach in a write to multiple data store entities, but it gives me error without specifying what could be wrong: here is the code and the error:

a!forEach(

      items: pv!getDocuments,

      expression: {

        a!entityData(

          entity: cons!CM_REF_CLAIM_DECLARATION_DOC,

          data: 'type!{urn:com:appian:types:CM}cm_ref_claim_declaration_doc'(

            idClaimDeclDoc: index(fv!item, "documentId", null),

            idDoc: index(fv!item, "documentId", null),

            idClaimDecl: pv!id_claim_declaration,

            createdBy: index(fv!item, "documentLoadUser", null),

            createdOn: index(fv!item, "documentLoadDateTime", null)

          )

        ),

        if(

          or(

            a!isNotNullOrEmpty(fv!item.letterTemplate),

            a!isNotNullOrEmpty(fv!item.letterCreationDate)

          ),

          a!entityData(

            entity: cons!CM_DSE_LETTER,

            data: 'type!{urn:com:appian:types:CM}cm_letter'(

              idClaimDecl: pv!id_claim_declaration,

              idClaim: pv!claimDeclaration.idClaim,

              idRisk: pv!claimDeclaration.idRisk,

              sentDate: index(fv!item, "letterSentDate", null),

              idDoc: index(fv!item, "documentId", null),

              createdBy: index(fv!item, "letterCreationUser", null),

              createdOn: index(fv!item, "letterCreationDate", null),

              receivedDate: index(fv!item, "documentReceptionDate", null)

            )

          ),

          {}

        ),

        a!entityData(

          entity: cons!CM_DSE_DOCUMENT,

          data: 'type!{urn:com:appian:types:CM}cm_document'(

            idDoc: index(fv!item, "documentId", null),

            docName: index(fv!item, "docName", null),

            docDescription: index(fv!item, "documentDescription", null),

            receiptDate: index(fv!item, "documentReceptionDate", null),

            uploadedDate: index(fv!item, "documentLoadDateTime", null),

            uploadOwner: index(fv!item, "documentLoadUser", null),

            idDocMacroCategory: index(fv!item, "documentIdMacroCategory", null),

            idDocMicroCategory: index(fv!item, "documentIdMicroCategory", null),

            status: index(fv!item, "letterStatus", null),

            sendLetterDate: index(fv!item, "letterSentDate", null),

            createdBy: index(fv!item, "documentLoadUser", null),

            createdOn: index(fv!item, "documentLoadDateTime", null),

            enrichDate: now()

          )

        )

      }

    )

Is the "forEach" a problem? How should I write it then?