[gtk/bilelmoussaoui/entry-completion] entry completion: add checks that entry is set already

[Bilal Elmoussaoui <bilelmoussaoui src gnome org>]

commit 883e8328e0ef45768126d3b52dc14b2a95f8ce4d
Author: Bilal Elmoussaoui <belmouss redhat com>
Date:   Tue Feb 8 10:51:38 2022 +0100

    entry completion: add checks that entry is set already
    
    If any of the APIs that assumes that the entry is set already is used
    before having one already set, things break pretty badly.
    
    Fixes a downstream issue reported at https://github.com/gtk-rs/gtk4-rs/issues/873

 gtk/gtkentrycompletion.c | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/gtk/gtkentrycompletion.c b/gtk/gtkentrycompletion.c
index 408047adf0..ef4985af72 100644
--- a/gtk/gtkentrycompletion.c
+++ b/gtk/gtkentrycompletion.c
@@ -1211,6 +1211,8 @@ gtk_entry_completion_match_selected (GtkEntryCompletion *completion,
                                      GtkTreeModel       *model,
                                      GtkTreeIter        *iter)
 {
+  g_assert (completion->entry != NULL);
+
   char *str = NULL;
 
   gtk_tree_model_get (model, iter, completion->text_column, &str, -1);
@@ -1229,6 +1231,8 @@ gtk_entry_completion_cursor_on_match (GtkEntryCompletion *completion,
                                       GtkTreeModel       *model,
                                       GtkTreeIter        *iter)
 {
+  g_assert (completion->entry != NULL);
+
   gtk_entry_completion_insert_completion (completion, model, iter);
 
   return TRUE;
@@ -1317,6 +1321,8 @@ static gboolean
 gtk_entry_completion_real_insert_prefix (GtkEntryCompletion *completion,
                                          const char         *prefix)
 {
+  g_assert (completion->entry != NULL);
+
   if (prefix)
     {
       int key_len;
@@ -1417,6 +1423,8 @@ gtk_entry_completion_insert_completion (GtkEntryCompletion *completion,
 void
 gtk_entry_completion_insert_prefix (GtkEntryCompletion *completion)
 {
+  g_return_if_fail (completion->entry != NULL);
+
   gboolean done;
   char *prefix;
   GtkText *text = gtk_entry_get_text_widget (GTK_ENTRY (completion->entry));