Since some code needs flexibility in error handling, where hardcoded error value of -1 wasn't handy, o3tl::convertToHex was changed to accept the error value as its template parameter. Change-Id: Ifc771cc8fa29a801d4556dea969fc3ea7e620df5 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/199367 Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com> Tested-by: Jenkins