`g?` cause index nil

[cxwx]

press g? in pantran cause

E5108: Error executing lua ...hare/nvim/lazy/pantran.nvim/lua/pantran/utils/buffer.lua:67: attempt to index field 'rhs' (a nil value)
stack traceback:
        ...hare/nvim/lazy/pantran.nvim/lua/pantran/utils/buffer.lua:67: in function 'get_mappings'
        ...cal/share/nvim/lazy/pantran.nvim/lua/pantran/ui/help.lua:59: in function 'toggle'
        .../share/nvim/lazy/pantran.nvim/lua/pantran/ui/actions.lua:13: in function 'rhs'
        ...share/nvim/lazy/pantran.nvim/lua/pantran/ui/controls.lua:100: in function <...share/nvim/lazy/pantran.nvim/lua/pantran/ui/controls.lua:100>
        [string ":lua"]:1: in main chunk