targets="msg" + ui2: a kind="confirm" msg immediately after a kind="empty" msg sends the confirm content to "msg" instead of "dialog"

Problem

"confirm" messages should go to the ui2 dialog window next to the confirmation prompt in the cmdline. This is normally the case, but when a kind="empty" message is processed, it leaves the messaging system in a state such that if the next message is kind="confirm", it is incorrectly sent to the "msg" window.

If default target is set to "cmd", this does not happen.

Steps to reproduce

1. create a minimal init.lua (the inputlist keymap is just for convenience of generating a confirm message)

require("vim._core.ui2").enable({
  msg = { targets = "msg" }
})

vim.keymap.set({"n"}, "<Enter>", function()
  vim.fn.inputlist({
    " item 1 ",
    " item 2 ",
    " item 3 "
  })
end)

1. emit a kind="confirm" message after doing something that causes a kind="empty" message to be processed

for example

nvim --clean -u init.lua

then

• : to enter cmdline
• <Esc> to abort and send empty message
• <Enter> to open a confirm message (in this case an inputlist)
• see that the confirm content is not in the dialog window

Here's a video demonstration

https://github.com/user-attachments/assets/60e364bc-f360-4030-8ad0-3672e4035d1f

Expected behavior

Confirm messages belong in the dialog window next to the confirmation prompt. Concretely, kind="confirm" message should be routed to "dialog" in the case outline above

System info

• Nvim version (nvim -v): v0.13.0-dev-1758 gb4528ba65c neovim/neovim@b4528ba65c
• Vim (not Nvim) behaves the same?: ?
• Operating system/version: Linux 7.1.12-100.fc43.x86_64
• Terminal name/version: ghostty 1.3.1-4.fc43
• $TERM environment variable: xterm-ghostty
• Installation: built from source make CMAKE_BUILD_TYPE=RelWithDebInfo CMAKE_INSTALL_PREFIX=$HOME/opt/nvim && make install