How to add new string to errorformat in init.lua

[Heryz1]

Hello everyone,

I want to jump through Python backtrace in neovim quickfix list.
To do that, I added the following ex-command :set errorformat+=%.%#File\ \"%f\"\\,\ line\ %l%.%# and this command works well.
What I would like now is to add, this command in my init.lua, But when I add the previous line, neovim raises errors when I populate the quickfix List.
This is the command I added to my init.lua : vim.opt.errorformat:append { "%.%#File \"%f\"\\, line %l%.%#" }.

Here is the error when I populate the quickfix list :
Error detected while processing function AsyncRun_Job_OnTimer[12]..<SNR>24_AsyncRun_Job_Update[40]..<SNR>24_AppendText: line 33: E377: Invalid %- in format string

Do you know how to append a new string to errorFormat ?

Thank you

[zeertzjq]

This seems to be a bug in vim.opt. It treats escaped commas as separators.

[Heryz1]

I think It is a normal behavior for errorformat to handle commas as a special characters.

The thing is, even vim.opt.errorformat:append('foo%f') does not work which is weird