patch 8.2.1428: Vim9: :def function does not abort on nested function error

Problem:    Vim9: :def function does not abort on nested function error.
Solution:   Check whether an error message was given. (closes #6691)
diff --git a/src/version.c b/src/version.c
index 63c9c3d..46d027d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1428,
+/**/
     1427,
 /**/
     1426,