home: vim: signtoggle: only show signs if 'number'

If a buffer doesn't show a number column, I probably also don't want a
sign column to be toggled on/off in there.

modules/home/vim/plugin/signtoggle.lua

@@ -1,17 +1,21 @@
 local signtoggle = vim.api.nvim_create_augroup("signtoggle", { clear = true })
 
--- Only show sign column for the currently focused buffer
+-- Only show sign column for the currently focused buffer, if it has a number column
 vim.api.nvim_create_autocmd({ "BufEnter", "FocusGained", "WinEnter" }, {
     pattern = "*",
     group = signtoggle,
     callback = function()
+        if vim.opt.number:get() then
             vim.opt.signcolumn = "yes"
+        end
     end,
 })
 vim.api.nvim_create_autocmd({ "BufLeave", "FocusLost", "WinLeave" }, {
     pattern = "*",
     group = signtoggle,
     callback = function()
+        if vim.opt.number:get() then
             vim.opt.signcolumn = "no"
+        end
     end,
 })