markdown: Fix possible crasher

Always ensure that the viewer's internal GString buffer is created
just to be safe. Also ensure the viewer is always updated which will
make sure the internal buffer is always created anyway.

markdown/src/plugin.c

@@ -62,10 +62,12 @@ static void on_view_pos_notify(GObject *obj, GParamSpec *pspec, MarkdownViewer *
 /* Main plugin entry point on plugin load. */
 void plugin_init(GeanyData *data)
 {
+  gint page_num;
   gchar *conf_fn;
   MarkdownConfig *conf;
   MarkdownConfigViewPos view_pos;
   GtkWidget *viewer;
+  GtkNotebook *nb;
 
   /* Setup the config object which is needed by the view. */
   conf_fn = g_build_filename(geany->app->configdir, "plugins", "markdown",
@@ -84,16 +86,17 @@ void plugin_init(GeanyData *data)
     GTK_POLICY_AUTOMATIC, GTK_POLICY_AUTOMATIC);
 
   if (view_pos == MARKDOWN_CONFIG_VIEW_POS_MSGWIN) {
-    gtk_notebook_append_page(
-      GTK_NOTEBOOK(geany->main_widgets->message_window_notebook),
+    nb = GTK_NOTEBOOK(geany->main_widgets->message_window_notebook);
+    page_num = gtk_notebook_append_page(nb,
       g_scrolled_win, gtk_label_new(MARKDOWN_PREVIEW_LABEL));
   } else {
-    gtk_notebook_append_page(
-      GTK_NOTEBOOK(geany->main_widgets->sidebar_notebook),
+    nb = GTK_NOTEBOOK(geany->main_widgets->sidebar_notebook);
+    page_num = gtk_notebook_append_page(nb,
       g_scrolled_win, gtk_label_new(MARKDOWN_PREVIEW_LABEL));
   }
 
   gtk_widget_show_all(g_scrolled_win);
+  gtk_notebook_set_current_page(nb, page_num);
 
   g_signal_connect(conf, "notify::view-pos", G_CALLBACK(on_view_pos_notify), viewer);
 
@@ -112,6 +115,8 @@ void plugin_init(GeanyData *data)
   /* Prevent segfault in plugin when it registers GTypes and gets unloaded
    * and when reloaded tries to re-register the GTypes. */
   plugin_module_make_resident(geany_plugin);
+
+  update_markdown_viewer(MARKDOWN_VIEWER(viewer));
 }
 
 /* Cleanup resources on plugin unload. */
@@ -225,4 +230,6 @@ on_view_pos_notify(GObject *obj, GParamSpec *pspec, MarkdownViewer *viewer)
   gtk_notebook_set_current_page(newnb, page_num);
 
   g_object_unref(g_scrolled_win); /* The new notebook owns it now */
+
+  update_markdown_viewer(viewer);
 }

markdown/src/viewer.c

@@ -299,11 +299,18 @@ static gchar *
 markdown_viewer_get_html(MarkdownViewer *self)
 {
   gchar *md_as_html, *html = NULL;
+
+  /* Ensure the internal buffer is created */
+  if (!self->priv->text) {
+    update_internal_text(self, "");
+  }
+
   md_as_html = mkd_compile_document(self->priv->text->str, 0);
   if (md_as_html) {
     html = template_replace(self, md_as_html);
     g_free(md_as_html);
   }
+
   return html;
 }