patch 8.2.4231: Vim9: map() gives type error when type was not declared

Problem:    Vim9: map() gives type error when type was not declared.
Solution:   Only check the type when it was declared, like extend() does.
            (closes #9635)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4231,
 /**/
     4230,
 /**/