Does SliceMap support UDT unmarshalling?

Using `iter.SliceMap()` on a query result (iter) for a table containing a list of frozen UDTs gives
`runtime error: slice bounds out of range`

However, it works when I manually scan each field with `iter.Scan()`

Does it mean that SliceMap does not support UDT?

Start by reproducing the reported failure through iter.SliceMap() on a query result containing a list of frozen UDTs, then compare it with manual field handling through iter.Scan(). Determine whether the runtime slice-bounds error is specific to UDT unmarshalling and document the expected behavior or a focused failing test.

Written by the indexing model from the issue text.