patch 8.2.1826: Vim9: cannot use a {} block at script level

Problem:    Vim9: cannot use a {} block at script level.
Solution:   Recognize a {} block.
diff --git a/src/errors.h b/src/errors.h
index cddd691..c2dc633 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -278,4 +278,6 @@
 	INIT(= N_("E1126: Cannot use :let in Vim9 script"));
 EXTERN char e_missing_name_after_dot[]
 	INIT(= N_("E1127: Missing name after dot"));
+EXTERN char e_endblock_without_block[]
+	INIT(= N_("E1128: } without {"));
 #endif