patch 8.2.2323: Vim9: error when inferring type from empty dict/list

Problem:    Vim9: error when inferring type from empty dict/list.
Solution:   When the member is t_unknown use t_any. (closes #7009)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index a6bb565..94f30d4 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -1899,7 +1899,10 @@
     }
     // change dict type to dict member type
     if (type->tt_type == VAR_DICT)
-	((type_T **)stack->ga_data)[stack->ga_len - 1] = type->tt_member;
+    {
+	((type_T **)stack->ga_data)[stack->ga_len - 1] =
+		      type->tt_member == &t_unknown ? &t_any : type->tt_member;
+    }
 
     return OK;
 }
@@ -3793,7 +3796,12 @@
 		    return FAIL;
 		}
 		if ((*typep)->tt_type == VAR_DICT)
+		{
 		    *typep = (*typep)->tt_member;
+		    if (*typep == &t_unknown)
+			// empty dict was used
+			*typep = &t_any;
+		}
 		else
 		{
 		    if (need_type(*typep, &t_dict_any, -2, cctx,
@@ -3831,7 +3839,12 @@
 		else
 		{
 		    if ((*typep)->tt_type == VAR_LIST)
+		    {
 			*typep = (*typep)->tt_member;
+			if (*typep == &t_unknown)
+			    // empty list was used
+			    *typep = &t_any;
+		    }
 		    if (generate_instr_drop(cctx,
 			     vtype == VAR_LIST ?  ISN_LISTINDEX : ISN_ANYINDEX,
 								    1) == FAIL)