Simple editable grid with document upload field saves OK except for when there are no rows

Hi all,

I have a simple editable grid with a file upload field and a dropdown field.  See screenshot attached.  With this, the interface saves ok and I have my data saved in my rule inputs.  However, then I try to submit the form without any data in grid (no rows), I get this error message - "Could not display interface. Please check definition and inputs.
Interface Definition: Expression evaluation error [evaluation ID = C163B2D3] : An error occurred while executing a save: Expression evaluation error: You must specify a variable to save into, such as ri!name << fn!sum. Received: RQ_Document_Uploads?list."

Any ideas why I am getting this error?  I am also attaching my editable grid SAIL code with this message.

Thanks

a!gridLayout(
  label: "",
  headerCells: {
    a!gridLayoutHeaderCell(label: "File"),
    a!gridLayoutHeaderCell(label: "File Type"),
    a!gridLayoutHeaderCell(label: "")
  },
  columnConfigs: {
    a!gridLayoutColumnConfig(width: "DISTRIBUTE", weight: 4),
    a!gridLayoutColumnConfig(width: "DISTRIBUTE", weight: 2),
    a!gridLayoutColumnConfig(width: "ICON")
  },
  rows: {
    a!forEach(
      items: ri!documents,
      expression: a!gridRowLayout(
        contents: {
          a!fileUploadField(
            label: "File Upload",
            labelPosition: "COLLAPSED",
            target: cons!RQ_UPLOADS_FOLDER,
            maxSelections: 1,
            value: fv!item.document,
            saveInto: fv!item.document,
            required: true,
            validations: {}
          ),
          a!dropdownField(
            label: "Dropdown",
            labelPosition: "COLLAPSED",
            placeholderLabel: "--- Select a Value ---",
            choiceLabels: {"Memo", "Invoice", "Product Brochure", "Receipt", "Check/Bank Draft", "Letter", "Other"},
            choiceValues: {"Memo", "Invoice", "Product Brochure", "Receipt", "Check/Bank Draft", "Letter", "Other"},
            value: fv!item.documentType,
            saveInto: fv!item.documentType,
            validations: {}
          ),                                                                                                                                                                                                                                                                                                                                                                                                     

          a!richTextDisplayField(
            value: {
              a!richTextIcon(
                icon: "times",
                link: a!dynamicLink(saveInto: {
                  a!save(ri!documents, remove(ri!documents, fv!index))
                }),
                linkStyle: "STANDALONE",
                color: "NEGATIVE")
            }
          )
        }
      )
    ),
    a!gridRowLayout(
      contents: {
        a!textField(readOnly: true),
        a!textField(readOnly: true),
        a!textField(readOnly: true)
      }
    )
  },
  addRowLink: 
  a!dynamicLink(
    label: if( or(isnull(ri!documents), length(ri!documents)>0),"Add Another Document", "Add New Document"),
    saveInto: {
      a!save(ri!documents, append(ri!documents, {document: "", documentType: null}))
    }
  ),
  rowHeader: 1
)