patch 8.2.0493: Vim9: some error messages not tested

Problem:    Vim9: some error messages not tested.
Solution:   Add more tests.  Fix uncovered bugs.
diff --git a/src/version.c b/src/version.c
index 5fc599c..3686a1d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    493,
+/**/
     492,
 /**/
     491,