No separator between entry.source and entry.code in the msg_fmt function

[LimbicSys]

Describe the bug

local function msg_fmt(entry)
  return entry.message
    .. ' '
    .. entry.lnum + 1
    .. ':'
    .. entry.col + 1
    .. ':'
    .. entry.bufnr
    .. ' '
    .. (entry.source and entry.source or '')
    .. (entry.code and entry.code or '')
end

There should be a separator, e.g., a white space.

Steps to reproduce

Use Lspsaga show_line_diagnostics on error lines.

Expected behavior

Message like this.

Neovim version (nvim -v)

0.9.4

lspsaga commit

4e2b91c0db5654d625c4b4068d3e206c8535783c

Terminal name/version

wezterm 20230712-072601-f4abf8fd