patch 9.0.1999: Vim9: some error messages can be improved

Problem:  Vim9: some error messages can be improved
Solution: Mention the defining class for variable access error message

closes: #13272

Signed-off-by: Christian Brabandt <cb@256bit.org>
Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Co-authored-by: Ernie Rael <errael@raelity.com>
diff --git a/src/version.c b/src/version.c
index 5335352..8dea204 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1999,
+/**/
     1998,
 /**/
     1997,