patch 9.1.1401: list not materialized in prop_list()

Problem:  list not materialized in prop_list()
          (Nickwiz)
Solution: materialize list before accessing it

fixes: #17298
closes: #17349

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/textprop.c b/src/textprop.c
index d16f8ec..a06605d 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -1439,7 +1439,7 @@
 {
     int		*prop_ids;
     listitem_T	*li;
-    int		i;
+    int		i = 0;
     int		id;
     int		error;
 
@@ -1449,7 +1449,7 @@
     if (prop_ids == NULL)
 	return NULL;
 
-    i = 0;
+    CHECK_LIST_MATERIALIZE(l);
     FOR_ALL_LIST_ITEMS(l, li)
     {
 	error = FALSE;