tdf#158379 check if PageDesc's m_pPSName is a nullptr

Change-Id: If9f6d695d40c1d55ee2dfbdf1e3523b33343d7ce
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/160504
Tested-by: Jenkins
Reviewed-by: Patrick Luby <plubius@libreoffice.org>
diff --git a/i18nutil/source/utility/paper.cxx b/i18nutil/source/utility/paper.cxx
index f88510c..399b329 100644
--- a/i18nutil/source/utility/paper.cxx
+++ b/i18nutil/source/utility/paper.cxx
@@ -400,8 +400,7 @@ PaperInfo::PaperInfo(tools::Long nPaperWidth, tools::Long nPaperHeight)

OString PaperInfo::toPSName(Paper ePaper)
{
    return static_cast<size_t>(ePaper) < nTabSize ?
        OString(aDinTab[ePaper].m_pPSName) : OString();
    return static_cast<size_t>(ePaper) < nTabSize && aDinTab[ePaper].m_pPSName ?  OString(aDinTab[ePaper].m_pPSName) : OString();
}

Paper PaperInfo::fromPSName(const OString &rName)