How to check if dt.AsEnumerable is Null before copying it UIPATH

Assuming I have understood the question properly, you have ran the query below which works fine except then the result is empty. This then fails as .CopyToDataTable() has nothing to copy.

dt1.AsEnumerable().Where(
    Function(row) Not dt2.AsEnumerable().Select(
        Function(r) r.Field(Of String)("Otsikko")
    ).Any(
        Function(x) x = row.Field(Of String)("Otsikko")
    )
).CopyToDataTable()

A solution would be to use a decision or if statement with the below code, this will return true if there is data in there, then you can use the above code to extract it, if it returns false, you can then handle this without an error getting thrown

dt1.AsEnumerable().Where(
    Function(row) Not dt2.AsEnumerable().Select(
        Function(r) r.Field(Of String)("Otsikko")
    ).Any(
        Function(x) x = row.Field(Of String)("Otsikko")
    )
).Any()