MSForms: Fix handling of drop-down form field after DOC import

In the properties dialog, code expected that the ODF_FORMDROPDOWN_RESULT
is not set in case of an empty list. This caused a crash.
The field popup window code expected that the list is not specified
when it is empty, but DOC import code sets ODF_FORMDROPDOWN_LISTENTRY
even if the list is empty.

Change-Id: If4c86fc5a08cdc578150afaa42ad7e86bdba9150
Reviewed-on: https://gerrit.libreoffice.org/68963Reviewed-by: Tamás Zolnai <tamas.zolnai@collabora.com>
Tested-by: Tamás Zolnai <tamas.zolnai@collabora.com>

sw/source/core/crsr/DropDownFormFieldButton.cxx

@@ -53,14 +53,15 @@ SwFieldDialog::SwFieldDialog(SwEditWin* parent, sw::mark::IFieldmark* fieldBM, l
         OUString sListKey = ODF_FORMDROPDOWN_LISTENTRY;
         sw::mark::IFieldmark::parameter_map_t::const_iterator pListEntries
             = pParameters->find(sListKey);
+        css::uno::Sequence<OUString> vListEntries;
         if (pListEntries != pParameters->end())
         {
-            css::uno::Sequence<OUString> vListEntries;
             pListEntries->second >>= vListEntries;
             for (OUString const& i : vListEntries)
                 aListBox->InsertEntry(i);
         }
-        else
+
+        if (vListEntries.getLength() == 0)
         {
             aListBox->InsertEntry(SwResId(STR_DROP_DOWN_EMPTY_LIST));
         }

sw/source/ui/fldui/DropDownFormFieldDialog.cxx

@@ -119,7 +119,8 @@ void DropDownFormFieldDialog::InitControls()
             {
                 sal_Int32 nSelection = -1;
                 pResult->second >>= nSelection;
-                m_xListItemsTreeView->select_text(vListEntries[nSelection]);
+                if (vListEntries.getLength() > nSelection)
+                    m_xListItemsTreeView->select_text(vListEntries[nSelection]);
             }
         }
     }