get rid of "A formula in this worksheet contains one or more invalid references"

Hi everyone,
I have a workbook in which there are many charts referring to range names.
The range names have been defined using a combination of "OFFSET" and "Countnumber", such that they change size as the values change.
Sometimes these ranges are empty because there are no values, only a "#NA" in the first cell and excel returns me the annoying message
"A formula in this worksheet contains one or more invalid references".

What can I do to get rid of that?
I know the code

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but I don't know where to write that to be valid for the whole workbook and forever!

Thanks in advance

Prevent the error from occurring in the first place, ie

IF(ISNA(formula),"",formula)

change the definition of countnumber so it is always at least 1 using
=MAX(current_formula,1)