fix(stars): Ignore stars node that end on column 0

This issue happens when deleting the headline

Author: kristijanhusak

lua/orgmode/colors/highlighter/stars.lua

@@ -31,6 +31,10 @@ function OrgStars:on_line(bufnr, line)
 
   local _, end_col = node:end_()
 
+  if end_col <= 0 then
+    return
+  end
+
   vim.api.nvim_buf_set_extmark(bufnr, self.highlighter.namespace, line, 0, {
     end_row = line,
     end_col = end_col - 1,