fdo#62682 bandaid fix for hyperlink export crash

Fixes the crash, but the deeper problem is that client code gets
confused about portion count, does not expect field to span more
than one line.

Change-Id: I237f3bbd16265597ee0639e77dd561d6c7f2cec8

filter/source/svg/svgwriter.cxx

@@ -1650,7 +1650,7 @@ void SVGTextWriter::writeTextPortion( const Point& rPos,
         sal_Int32 nStartPos;
         while( bNotSync )
         {
-            if( mnLeftTextPortionLength <= 0 )
+            if( mnLeftTextPortionLength <= 0  || !mrCurrentTextPortion.is() )
             {
                 if( !nextTextPortion() )
                     break;