tdf#126000 Crash deleting template

regression from
    commit 72c191e046112df73c66be8dc8d1bec5a546fa60
    Date:   Wed Sep 19 12:11:38 2018 +0200
    loplugin:useuniqueptr in ThumbnailView

Reviewed-on: https://gerrit.libreoffice.org/74362
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
(cherry picked from commit 801bb2d4002cf2034315875440a6aee358951eb9)
Reviewed-on: https://gerrit.libreoffice.org/74372
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

Change-Id: I9bdcec5c2f14b1bd33998041d4b2d8cd2f7be052
Reviewed-on: https://gerrit.libreoffice.org/74428
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
Tested-by: Jenkins
diff --git a/sfx2/source/control/thumbnailview.cxx b/sfx2/source/control/thumbnailview.cxx
index 83fae8c..df44632 100644
--- a/sfx2/source/control/thumbnailview.cxx
+++ b/sfx2/source/control/thumbnailview.cxx
@@ -962,12 +962,16 @@

    if ( nPos < mFilteredItemList.size() ) {

        // keep it alive until after we have deleted it from the filter item list
        std::unique_ptr<ThumbnailViewItem> xKeepAliveViewItem;

        // delete item from the thumbnail list
        for (size_t i = 0, n = mItemList.size(); i < n; ++i)
        for (auto it = mItemList.begin(); it != mItemList.end(); ++it)
        {
            if (mItemList[i]->mnId == nItemId)
            if ((*it)->mnId == nItemId)
            {
                mItemList.erase(mItemList.begin()+i);
                xKeepAliveViewItem = std::move(*it);
                mItemList.erase(it);
                break;
            }
        }
@@ -982,7 +986,6 @@
            maItemStateHdl.Call(*it);
        }

        delete *it;
        mFilteredItemList.erase( it );
        mpStartSelRange = mFilteredItemList.end();
    }