prueba con find

plugin/todoer.lua

@@ -57,8 +57,8 @@ local function add_todo()
 	local closedpattern = "^%s*%- %[[x]%]"
 
 	local line = vim.api.nvim_get_current_line()
-	local spaces = string.match(line, "^%s*")
-	print(spaces)
+	local i, spaces = string.find(line, "^%s*")
+	print(i, spaces)
 
 	-- if not string.match(line, openpattern) and not string.match(line, closedpattern) then
 	-- 	line = spaces .. "- [ ] " .. line