sy#sign#get_current_signs(sy) raise 'buffer)' not in dict

Hello,

maybe it is because of multiple overrides in my vim profile, or vim-signature plugin, but
in `function! sy#sign#get_current_signs(sy) abort` because of vim doing strange things with object property processing.

let signlist = sy#util#get_signs(a:sy.buffer)
-> raise 'buffer)' not in dict

If i replace this by a more failsafe code :

let signlist = sy#util#get_signs(get(a:sy, 'buffer', ''))

it looks ok

Vim version : NVIM v0.9.5

Thx for your plugin anyway.

Start in sy#sign#get_current_signs(sy), then inspect sy#util#get_signs and reproduce the error on the reported Neovim version. Verify that sign lookup no longer raises when the sy object lacks buffer, while preserving normal sign retrieval.

Written by the indexing model from the issue text.