Array/composite type member assignment support?

https://www.postgresql.org/message-id/flat/PH0PR21MB132823A46AA36F0685B7A29AD8BD9%40PH0PR21MB1328.namprd21.prod.outlook.com
shows a crash in member assignment in PG14:
```
UPDATE domain_indirection_test SET domain_array[0].if2 = 5;
server closed the connection unexpectedly
```

Could be an interesting syntax feature to support.