Question: Should cells containing errors return missing?

[TimG1964]

julia> XLSX.getcell(f[1], "M4")
XLSX.Cell(M4, "e", "", "#DIV/0!", "", XLSX.Formula("1/0", nothing, nothing, nothing))

julia> f[1]["M4"]
missing

I ask this because I'm looking at how FileIO.jl and the related ExcelFiles.jl handle Excel files. Currently they are broken since ExcelReaders.jl stopped supporting .xlsx files around two years ago. However, it is clear from the test suite for ExcelFiles.jl that it previously expected cells like the above to return a ExcelReaders.ExcelErrorCell.

Maybe it would be possible for XLSX.jl to return something other than missing when cells contain errors. Maybe this would be too breaking?

Errors include #DIV/0!, #REF!, NAME?, #N/A, #SPILL! and possibly others.

Do others have a view on this?

[TimG1964]

On the face of it, this is a one line change (in cell.jl)

    if iserror(cell)
#        return missing
        return cell.value
    end

To mitigate the change, could perhaps add a kw option in readtable to convert errors to missing.

[jeff-emanuel]

FWIW, I have a helper getdata function that returns my own ErrorValue type wrapping the cell value. This allows me to dispatch for cell error values versus strings. XLSX.getdata returns Dates, Ints, Float64s, etc. It could (should) define an error type to wrap error values, but I do see where it would be breaking. My helper detects an error by checking for missing.