Cannot quit after attaching buffer to arbitrary REPL language

[fasterius]

Thanks for the wonderful plugin! I'm interested in transitioning from Vim Slime to Iron, but I haven't quite got some things working, the following being one of them:

Some common formats for data analysis are R Markdown and Quarto, which are their own filetypes (rmd and quarto, respectively). Attaching a rmd buffer to e.g. an r REPL works fine using :IronAttach r - I can even send code and work with it just fine. I can't quit using the builtin exit mapping, though, I only get this error:

E5108: Error executing lua: .../.local/share/nvim/lazy/iron.nvim/lua/iron/lowlevel.lua:156: attempt to index local 'meta' (a nil value)
stack traceback:
        .../.local/share/nvim/lazy/iron.nvim/lua/iron/lowlevel.lua:156: in function 'send_to_repl'
        .../.local/share/nvim/lazy/iron.nvim/lua/iron/core.lua:144: in function <...local/share/nvim/lazy/iron.nvim/lua/iron/core.lua:140>

I can, however, close the REPL window with :lua require('iron.core').close_repl('r'). Is this the intended function and I'm missing something, or is it a bug?