editeng: do not throw from QueryValue implementation

None of the other QueryValue throw; in case of a problem they return
false without initialising the Any.

On the one hand, it would be useful to throw an exception for this
special property that has now become Write-Only, so that API users
get a better hint what is going wrong; on the other hand, it breaks
various other things like the various multi-property interfaces that
call QueryValue for multiple items (there are 3 such loops in
SwAccessibleParagraph alone).

(throw was introduced in 7a8ed362eb163ac15a000ba1cfc74b58315800a1)

It turns out there is even a test for the exception on ToX.

Change-Id: Id60ff43544f7399ce869227bfd6fb933dbaea3be
Reviewed-on: https://gerrit.libreoffice.org/61719
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Signed-off-by: Michael Meeks <michael.meeks@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/62331
diff --git a/editeng/source/items/frmitems.cxx b/editeng/source/items/frmitems.cxx
index d5c2e7a..e3ca3a1 100644
--- a/editeng/source/items/frmitems.cxx
+++ b/editeng/source/items/frmitems.cxx
@@ -3316,7 +3316,8 @@ bool SvxBrushItem::QueryValue( uno::Any& rVal, sal_uInt8 nMemberId ) const

        case MID_GRAPHIC_URL:
        {
            throw uno::RuntimeException("Getting from this property is not supported");
            SAL_INFO("editeng.items", "Getting GraphicURL property is not supported");
            return false;
        }
        break;
        case MID_GRAPHIC:
diff --git a/sw/source/core/unocore/unoidx.cxx b/sw/source/core/unocore/unoidx.cxx
index f2550b3..76f4faf 100644
--- a/sw/source/core/unocore/unoidx.cxx
+++ b/sw/source/core/unocore/unoidx.cxx
@@ -36,6 +36,7 @@
#include <cppuhelper/supportsservice.hxx>
#include <vcl/svapp.hxx>
#include <editeng/unolingu.hxx>
#include <editeng/memberids.h>
#include <hints.hxx>
#include <cmdid.h>
#include <swtypes.hxx>
@@ -886,6 +887,11 @@ SwXDocumentIndex::getPropertyValue(const OUString& rPropertyName)
            "Unknown property: " + rPropertyName,
            static_cast< cppu::OWeakObject * >(this));
    }
    // TODO: is this the best approach to tell API clients about the change?
    if (pEntry->nWID == RES_BACKGROUND && pEntry->nMemberId == MID_GRAPHIC_URL)
    {
        throw uno::RuntimeException("Getting GraphicURL property is not supported");
    }

    SwSectionFormat *const pSectionFormat( m_pImpl->GetSectionFormat() );
    SwTOXBase* pTOXBase = nullptr;