Resolves: tdf#113230 crash in finishParagraph

Change-Id: I94535a51a87be097ff7356edff935877b42c3272
Reviewed-on: https://gerrit.libreoffice.org/43598Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

writerfilter/source/dmapper/DomainMapper_Impl.cxx

@@ -4857,7 +4857,10 @@ void DomainMapper_Impl::StartOrEndBookmark( const OUString& rId )
             {
                 uno::Reference< text::XTextCursor > xCursor = xTextAppend->createTextCursorByRange( xTextAppend->getEnd() );
 
-                if(!bIsAfterDummyPara)
+                if (!xCursor)
+                    return;
+
+                if (!bIsAfterDummyPara)
                     bIsStart = !xCursor->goLeft(1, false);
                 xCurrent = xCursor->getStart();
             }