[goffice] Plot: avoid some criticals with missing axis.

[Morten Welinder <mortenw src gnome org>]

commit bab2ae03c95737f680d4330db8f452b18a517d23
Author: Morten Welinder <terra gnome org>
Date:   Mon Apr 27 17:40:25 2015 -0400

    Plot: avoid some criticals with missing axis.

 plugins/plot_barcol/gog-1.5d.c |   24 +++++++++++++-----------
 1 files changed, 13 insertions(+), 11 deletions(-)
---
diff --git a/plugins/plot_barcol/gog-1.5d.c b/plugins/plot_barcol/gog-1.5d.c
index b886eba..6482f9c 100644
--- a/plugins/plot_barcol/gog-1.5d.c
+++ b/plugins/plot_barcol/gog-1.5d.c
@@ -212,16 +212,18 @@ gog_plot1_5d_update (GogObject *obj)
                index_dim = series->base.values[0].data;
        }
 
-       if (model->num_elements != num_elements ||
-           model->implicit_index ^ (index_dim == NULL) ||
-           (index_dim != gog_axis_get_labels (iaxis, &plot_that_labeled_axis) &&
-            GOG_PLOT (model) == plot_that_labeled_axis)) {
-               model->num_elements = num_elements;
-               model->implicit_index = (index_dim == NULL);
-               gog_axis_bound_changed (iaxis, GOG_OBJECT (model));
-       } else {
-               if (index_changed)
+       if (iaxis) {
+               if (model->num_elements != num_elements ||
+                   model->implicit_index ^ (index_dim == NULL) ||
+                   (index_dim != gog_axis_get_labels (iaxis, &plot_that_labeled_axis) &&
+                    GOG_PLOT (model) == plot_that_labeled_axis)) {
+                       model->num_elements = num_elements;
+                       model->implicit_index = (index_dim == NULL);
                        gog_axis_bound_changed (iaxis, GOG_OBJECT (model));
+               } else {
+                       if (index_changed)
+                               gog_axis_bound_changed (iaxis, GOG_OBJECT (model));
+               }
        }
 
        model->num_series = num_series;
@@ -273,7 +275,7 @@ gog_plot1_5d_axis_get_bounds (GogPlot *plot, GogAxisType atype,
        GogAxis *iaxis = gog_plot1_5d_get_index_axis (model);
        GogAxis *vaxis = gog_plot1_5d_get_value_axis (model);
 
-       if (atype == gog_axis_get_atype (vaxis)) {
+       if (vaxis && atype == gog_axis_get_atype (vaxis)) {
                bounds->val.minima = model->minima;
                bounds->val.maxima = model->maxima;
                if (model->type == GOG_1_5D_AS_PERCENTAGE) {
@@ -303,7 +305,7 @@ gog_plot1_5d_axis_get_bounds (GogPlot *plot, GogAxisType atype,
                                bounds->val.maxima = 0.;
                }
                return NULL;
-       } else if (atype == gog_axis_get_atype (iaxis)) {
+       } else if (iaxis && atype == gog_axis_get_atype (iaxis)) {
                GSList *ptr;
 
                bounds->val.minima = 1.;