tdf#121198: fix crash in SdrPage::GetPageNum()

Regression from 9348b322a5c230dfcc2231661b73e480b130fcd9

Change-Id: Ibf9d6b65f0dbcc3a751e3ac5f3dbc28d908d6c25
Reviewed-on: https://gerrit.libreoffice.org/62952
Tested-by: Jenkins
(cherry picked from commit ebd24b39eee5ac72d33ad731e31469cf8f330631)
Reviewed-on: https://gerrit.libreoffice.org/62965
Reviewed-by: Xisco FaulĂ­ <xiscofauli@libreoffice.org>
diff --git a/sd/source/ui/slidesorter/controller/SlsInsertionIndicatorHandler.cxx b/sd/source/ui/slidesorter/controller/SlsInsertionIndicatorHandler.cxx
index acd93d2..4bbbbd4 100644
--- a/sd/source/ui/slidesorter/controller/SlsInsertionIndicatorHandler.cxx
+++ b/sd/source/ui/slidesorter/controller/SlsInsertionIndicatorHandler.cxx
@@ -220,7 +220,7 @@ bool InsertionIndicatorHandler::IsInsertionTrivial (
    // to check that the insertion position is not directly in front or
    // directly behind the selection and thus moving the selection there
    // would not change the model.
    return nInsertionIndex >= nFirstIndex && nInsertionIndex < nLastIndex;
    return nInsertionIndex >= nFirstIndex && nInsertionIndex <= (nLastIndex+1);
}

bool InsertionIndicatorHandler::IsInsertionTrivial (const sal_Int8 nDndAction)