patch 8.2.4286: Vim9: strict type checking after copy() and deepcopy()

Problem:    Vim9: strict type checking after copy() and deepcopy().
Solution:   Allow type to change after making a copy. (closes #9644)
diff --git a/src/vim9execute.c b/src/vim9execute.c
index a45d7c5..cac8c51 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -4412,7 +4412,8 @@
 								       == NULL)
 		    {
 			SOURCING_LNUM = iptr->isn_lnum;
-			semsg(_(e_key_not_present_in_dictionary), iptr->isn_arg.string);
+			semsg(_(e_key_not_present_in_dictionary),
+							 iptr->isn_arg.string);
 			goto on_error;
 		    }
 		    // Put the dict used on the dict stack, it might be used by
@@ -4531,21 +4532,7 @@
 		break;
 
 	    case ISN_SETTYPE:
-		{
-		    checktype_T *ct = &iptr->isn_arg.type;
-
-		    tv = STACK_TV_BOT(-1);
-		    if (tv->v_type == VAR_DICT && tv->vval.v_dict != NULL)
-		    {
-			free_type(tv->vval.v_dict->dv_type);
-			tv->vval.v_dict->dv_type = alloc_type(ct->ct_type);
-		    }
-		    else if (tv->v_type == VAR_LIST && tv->vval.v_list != NULL)
-		    {
-			free_type(tv->vval.v_list->lv_type);
-			tv->vval.v_list->lv_type = alloc_type(ct->ct_type);
-		    }
-		}
+		set_tv_type(STACK_TV_BOT(-1), iptr->isn_arg.type.ct_type);
 		break;
 
 	    case ISN_2BOOL: