avoid crash on export of ooo121238-1.odt to rtf

Change-Id: I2ba426168f861e69ef81850bb23576036b30fc76

sw/source/filter/ww8/rtfattributeoutput.cxx

@@ -1823,6 +1823,8 @@ void RtfAttributeOutput::OutputFlyFrame_Impl(const sw::Frame& rFrame, const Poin
                 uno::Reference< awt::XControlModel > xControlModel =
                     pFormObj->GetUnoControlModel();
                 uno::Reference< lang::XServiceInfo > xInfo(xControlModel, uno::UNO_QUERY);
+                if (xInfo.is())
+                {
                     uno::Reference<beans::XPropertySet> xPropSet(xControlModel, uno::UNO_QUERY);
                     uno::Reference<beans::XPropertySetInfo> xPropSetInfo = xPropSet->getPropertySetInfo();
                     OUString sName;
@@ -2001,6 +2003,7 @@ void RtfAttributeOutput::OutputFlyFrame_Impl(const sw::Frame& rFrame, const Poin
                     m_aRun->append('}');
                 }
             }
+        }
 
         m_aRun->append('}');
     }