gtk_tree_view_scroll_to_cell: assertion 'tree_view->priv->tree != NULL' failed

on loading sw//qa/extras/layout/data/tdf125334.odt and double clicking
chart

Change-Id: I65b10c0223e9c217d77dc7daa73580fadffc32c1
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/155096
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>
diff --git a/chart2/source/controller/dialogs/tp_AxisPositions.cxx b/chart2/source/controller/dialogs/tp_AxisPositions.cxx
index 8a31c73..4e3e4bb 100644
--- a/chart2/source/controller/dialogs/tp_AxisPositions.cxx
+++ b/chart2/source/controller/dialogs/tp_AxisPositions.cxx
@@ -295,7 +295,7 @@ IMPL_LINK_NOARG(AxisPositionsTabPage, CrossesAtSelectHdl, weld::ComboBox&, void)

    if (m_xED_CrossesAt->get_text().isEmpty())
        m_xED_CrossesAt->GetFormatter().SetValue(0.0);
    if (m_xED_CrossesAtCategory->get_active() == -1)
    if (m_xED_CrossesAtCategory->get_active() == -1 && m_xED_CrossesAtCategory->get_count())
        m_xED_CrossesAtCategory->set_active(0);

    PlaceLabelsSelectHdl(*m_xLB_PlaceLabels);