patch 8.2.4554: Vim9: using null values not sufficiently tested

Problem:    Vim9: using null values not sufficiently tested.
Solution:   Add more tests.  Fix uncovered problem.
diff --git a/src/version.c b/src/version.c
index 0c90e2d..bdd9dd8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4554,
+/**/
     4553,
 /**/
     4552,