shell/window-preview-layout: Add precondition checks

It's good practice to guard public API against programmer errors,
so do that.

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6351

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2622>

diff --git a/src/shell-window-preview-layout.c b/src/shell-window-preview-layout.c
index 9cf6633b19b99bd4caf551c763e5ecdc7f3d0848..8d8596af42bdb8f0a621b446a8c4232002ba6809 100644 (file)
--- a/src/shell-window-preview-layout.c
+++ b/src/shell-window-preview-layout.c
@@ -366,6 +366,9 @@ shell_window_preview_layout_add_window (ShellWindowPreviewLayout *self,
   GHashTableIter iter;
   gpointer value;
 
+  g_return_val_if_fail (SHELL_IS_WINDOW_PREVIEW_LAYOUT (self), NULL);
+  g_return_val_if_fail (META_IS_WINDOW (window), NULL);
+
   priv = shell_window_preview_layout_get_instance_private (self);
 
   g_hash_table_iter_init (&iter, priv->windows);
@@ -425,6 +428,9 @@ shell_window_preview_layout_remove_window (ShellWindowPreviewLayout *self,
   GHashTableIter iter;
   gpointer key, value;
 
+  g_return_if_fail (SHELL_IS_WINDOW_PREVIEW_LAYOUT (self));
+  g_return_if_fail (META_IS_WINDOW (window));
+
   priv = shell_window_preview_layout_get_instance_private (self);
 
   g_hash_table_iter_init (&iter, priv->windows);
@@ -473,6 +479,8 @@ shell_window_preview_layout_get_windows (ShellWindowPreviewLayout *self)
   GHashTableIter iter;
   gpointer value;
 
+  g_return_val_if_fail (SHELL_IS_WINDOW_PREVIEW_LAYOUT (self), NULL);
+
   priv = shell_window_preview_layout_get_instance_private (self);
 
   g_hash_table_iter_init (&iter, priv->windows);