pipe_to() and move_messages() on same results

[Feli-xyz]

Doing some improvements to my config I'm stuck now. If it's not a bug any help will be welcome.

This works as expected

function pipe_code(mbox)
  selection =
      mbox.INBOX:contain_body('magic: ')

  selection:move_messages(mbox['INBOX/code'])
end

imapfilter: IMAP (3): 1098 NO [TRYCREATE] Mailbox doesn't exist: INBOX/code (0.001 + 0.000 secs).
1 messages moved from example@example.com@mailserver.com/INBOX to example@example.com@mailserver.com/INBOX/code.

and also does

function pipe_code(mbox)

  selection =
      mbox.INBOX:contain_body('magic: ')

  results = Set {}

  for _, mesg in ipairs(selection) do
      mbox, uid = table.unpack(mesg)
      from = mbox[uid]:fetch_field('From')
      from=string.match(from,'.*From:.*%<(.*)%>')
      body = mbox[uid]:fetch_body()
      code=string.match(body,'.*magic: (%d%d%d%d)')
		
      pipe_to('/var/local/imapfilter/test.sh', code .. '\n')

      table.insert(results, {mbox, uid})

  end

  results:delete_messages()
end

Fetched field "From" of example@example.com@mailserver.com/INBOX[36485].
Fetched the body of example@example.com@mailserver.com/INBOX[36485].

1 messages deleted in example@example.com@mailserver.com/INBOX.

but I can't find a solution for

--  results:delete_messages()
    results:move_messages(mbox['INBOX/code'])

Fetched field "From" of example@example.com@mailserver.com/INBOX[36486].
Fetched the body of example@example.com@mailserver.com/INBOX[36486].

imapfilter: /usr/local/share/imapfilter/mailbox.lua:186: bad argument #3 to 'copy' (string expected, got table)
stack traceback:
        [C]: in ?
        [C]: in field 'copy'
        /usr/local/share/imapfilter/mailbox.lua:186: in field '_copy_messages'
        /usr/local/share/imapfilter/mailbox.lua:724: in field 'move_messages'
        /usr/local/share/imapfilter/set.lua:230: in method 'move_messages'
        config-code.lua:58: in function 'pipe_code'
        config-code.lua:107: in main chunk

Versions:

imapfilter -V; lua -v
IMAPFilter 2.8.3  
Lua 5.4.8 

Thanks!