Error "P-1D" when reading an incorrect DateTime

[drasill]

Hi,

I have a document where the date seems to be -1, probably because of an export.

The Excel file is opened in libreoffice, where the date appears as "29/12/1899".

But the reader throws an Exception when stumbling on this value :
Exception with message 'DateInterval::__construct(): Unknown or bad format (P-1D)'.

[drasill]

Thank you for the merge !

Would you release a new version too, please ?

[adirfische]

Sure thing!