[gtk/gtk-4-6] inspector: Avoid a crash

[Matthias Clasen <matthiasc src gnome org>]

commit feb3d3b274b4426963567c28b842e8dbf68999dd
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Apr 3 15:53:34 2022 -0400

    inspector: Avoid a crash
    
    Attribute lists can be NULL, it turns out.

 gtk/inspector/prop-editor.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/gtk/inspector/prop-editor.c b/gtk/inspector/prop-editor.c
index db3d6f2c1b..05048f5472 100644
--- a/gtk/inspector/prop-editor.c
+++ b/gtk/inspector/prop-editor.c
@@ -405,7 +405,7 @@ attr_list_changed (GObject *object, GParamSpec *pspec, gpointer data)
 {
   GtkEntry *entry = GTK_ENTRY (data);
   GValue val = G_VALUE_INIT;
-  char *str;
+  char *str = NULL;
   const char *text;
   PangoAttrList *attrs;
 
@@ -413,7 +413,8 @@ attr_list_changed (GObject *object, GParamSpec *pspec, gpointer data)
   get_property_value (object, pspec, &val);
 
   attrs = g_value_get_boxed (&val);
-  str = pango_attr_list_to_string (attrs);
+  if (attrs)
+    str = pango_attr_list_to_string (attrs);
   if (str == NULL)
     str = g_strdup ("");
   text = gtk_editable_get_text (GTK_EDITABLE (entry));