fix: check for cursorline visibility (#165)

vim.opt.cursorline isn't enough to check if the cursorline is visible, since vim.opt.cursorlineopt can be set to "number", in which case the cursorline isn't truly visible, making the background behind the displayed diagnostics look strange

Author: spflaumer

lua/tiny-inline-diagnostic/highlights.lua

@@ -72,6 +72,17 @@ local function get_mixing_color(color)
   return get_highlight(color).bg
 end
 
+---Check if the cursorline is visible
+---@return boolean
+local function is_cursorline_visible()
+  if vim.opt.cursorline:get() then
+    local cursorline_opt = vim.opt.cursorlineopt:get()
+    return not (#cursorline_opt == 1 and cursorline_opt[1] == "number")
+  end
+
+  return false
+end
+
 ---@param blend BlendOptions
 ---@param default_hi DefaultHighlights
 function M.setup_highlights(blend, default_hi, transparent_bg)
@@ -84,10 +95,10 @@ function M.setup_highlights(blend, default_hi, transparent_bg)
   end
 
   local cursorline_hl = get_highlight("CursorLine")
-  local is_cursorline_enabled = vim.opt.cursorline:get()
+  local cursorline_is_visible = is_cursorline_visible()
   local has_cursorline_bg = cursorline_hl.bg ~= "None"
 
-  local cursor_line_color = (is_cursorline_enabled and has_cursorline_bg) and cursorline_hl
+  local cursor_line_color = (cursorline_is_visible and has_cursorline_bg) and cursorline_hl
     or { bg = "None" }
 
   local colors = {