abi#3623 RTF import: missing null pointer check

Change-Id: I5861e5fec0d822f42dfeb994500a818a968e69fb
diff --git a/writerfilter/qa/cppunittests/rtftok/data/pass/abi3623.rtf b/writerfilter/qa/cppunittests/rtftok/data/pass/abi3623.rtf
new file mode 100644
index 0000000..a47161a
--- /dev/null
+++ b/writerfilter/qa/cppunittests/rtftok/data/pass/abi3623.rtf
@@ -0,0 +1,7 @@
{\rtf1
{\stylesheet
{\s2\ls1\sbasedon0 heading 2;}
}
\s2
foo\par
}
diff --git a/writerfilter/source/dmapper/DomainMapper.cxx b/writerfilter/source/dmapper/DomainMapper.cxx
index b3932c3..904cd40 100644
--- a/writerfilter/source/dmapper/DomainMapper.cxx
+++ b/writerfilter/source/dmapper/DomainMapper.cxx
@@ -2015,7 +2015,7 @@ void DomainMapper::sprmWithProps( Sprm& rSprm, PropertyMapPtr rContext, SprmType
                {
                    const StyleSheetEntryPtr pParent = pStyleTable->FindStyleSheetByISTD(pEntry->sBaseStyleIdentifier);
                    const StyleSheetPropertyMap* pParentProperties = dynamic_cast<const StyleSheetPropertyMap*>(pParent ? pParent->pProperties.get() : 0);
                    if (pParentProperties->find(PROP_PARA_RIGHT_MARGIN) != pParentProperties->end())
                    if (pParentProperties && pParentProperties->find(PROP_PARA_RIGHT_MARGIN) != pParentProperties->end())
                        nParaRightMargin = pParentProperties->find(PROP_PARA_RIGHT_MARGIN)->second.getValue().get<sal_Int32>();
                }
                if (nParaRightMargin != 0)