[gnumeric] GnmSheetSel: add preconditions

[Morten Welinder <mortenw src gnome org>]

commit 42f454400b0a8978a32063e93d388e4f6f08494c
Author: Morten Welinder <terra gnome org>
Date:   Tue Apr 10 15:25:53 2018 -0400

    GnmSheetSel: add preconditions

 src/widgets/gnm-sheet-sel.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/src/widgets/gnm-sheet-sel.c b/src/widgets/gnm-sheet-sel.c
index b04db78..5b5778d 100644
--- a/src/widgets/gnm-sheet-sel.c
+++ b/src/widgets/gnm-sheet-sel.c
@@ -100,7 +100,7 @@ gnm_sheet_sel_init (GnmSheetSel *ss)
 
 static void
 gnm_sheet_sel_set_property (GObject *object, guint property_id,
-                              const GValue *value, GParamSpec *pspec)
+                           const GValue *value, GParamSpec *pspec)
 {
        GnmSheetSel *ss = (GnmSheetSel *)object;
 
@@ -116,7 +116,7 @@ gnm_sheet_sel_set_property (GObject *object, guint property_id,
 
 static void
 gnm_sheet_sel_get_property (GObject *object, guint property_id,
-                              GValue *value, GParamSpec *pspec)
+                           GValue *value, GParamSpec *pspec)
 {
        GnmSheetSel *ss = (GnmSheetSel *)object;
 
@@ -164,6 +164,8 @@ gnm_sheet_sel_set_sheets (GnmSheetSel *ss, GSList *sheets)
        GtkMenu *menu;
        GSList *l;
 
+       g_return_if_fail (GNM_IS_SHEET_SEL (ss));
+
         menu = GTK_MENU (gtk_menu_new ());
 
        for (l = sheets; l; l = l->next) {
@@ -201,6 +203,9 @@ cb_wb_changed (GnmWorkbookSel *wbs,
 void
 gnm_sheet_sel_link (GnmSheetSel *ss, GnmWorkbookSel *wbs)
 {
+       g_return_if_fail (GNM_IS_SHEET_SEL (ss));
+       g_return_if_fail (GNM_IS_WORKBOOK_SEL (wbs));
+
        g_signal_connect_object
                (wbs,
                 "notify::workbook", G_CALLBACK (cb_wb_changed),