patch 8.2.4280: list-dict test crashes

Problem:    list-dict test crashes.
Solution:   Check declared type for add().
diff --git a/src/version.c b/src/version.c
index 6d89615..978e869 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4280,
+/**/
     4279,
 /**/
     4278,
diff --git a/src/vim9expr.c b/src/vim9expr.c
index 6affac2..d36df84 100644
--- a/src/vim9expr.c
+++ b/src/vim9expr.c
@@ -759,7 +759,7 @@
 
 	    if (STRCMP(name, "add") == 0 && argcount == 2)
 	    {
-		type_T	    *type = get_type_on_stack(cctx, 1);
+		type_T	    *type = get_decl_type_on_stack(cctx, 1);
 
 		// add() can be compiled to instructions if we know the type
 		if (type->tt_type == VAR_LIST)