tdf#91140: tweak fix a bit, turns out xmloff was also passing empty URL

Change-Id: Ia6e1fbe18e72c9c06915e1b437076a1f56a6c206

sw/source/core/unocore/unoframe.cxx

@@ -259,6 +259,8 @@ bool BaseFrameProperties_Impl::FillBaseProperties(SfxItemSet& rToSet, const SfxI
     const bool bFillStyleUsed(pXFillStyleItem && pXFillStyleItem->hasValue() &&
         (pXFillStyleItem->get<drawing::FillStyle>() != drawing::FillStyle_SOLID
          || !pGrURL));
+    SAL_INFO_IF(pXFillStyleItem && pXFillStyleItem->hasValue() && !bFillStyleUsed,
+            "sw.uno", "FillBaseProperties: ignoring invalid FillStyle");
     const bool bXFillStyleItemUsed(
         bFillStyleUsed ||
         pXFillColorItem ||

xmloff/source/style/XMLBackgroundImageContext.cxx

@@ -389,7 +389,8 @@ void XMLBackgroundImageContext::EndElement()
     else if( GraphicLocation_NONE == ePos )
         ePos = GraphicLocation_TILED;
 
-    aProp.maValue <<= sURL;
+    if (!sURL.isEmpty())
+        aProp.maValue <<= sURL;
     aPosProp.maValue <<= ePos;
     aFilterProp.maValue <<= sFilter;
     aTransparencyProp.maValue <<= nTransparency;