patch 8.2.1949: Vim9: using extend() on null dict is silently ignored

Problem:    Vim9: using extend() on null dict is silently ignored.
Solution:   Give an error message.  Initialize a dict variable with an empty
            dictionary. (closes #7251)
diff --git a/src/version.c b/src/version.c
index d380452..112077a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1949,
+/**/
     1948,
 /**/
     1947,