Created attachment 45455 [details]
Illustration of IsError bug
Neither ISERR() nor ISERROR() nor ERRRORTYPE() correctly detects an error on nested formula. E.g. when one enters
it always returns "FALSE", regardless the existence of "NonExistingSheet" in current workbook.
In contrast, when for example cell A1 contains formula
evaluates to "TRUE", as expected.
The same holds for functions ISERROR() and ERRORTYPE().
Fixed in master:
This bug persist in versions 3.4.5. of LibreOffice
Pushed now to 3-4 too.