我想使用命令添加权限“管理员”，但输出错误 “ NoneType”没有属性“颜色”
@bot.command(pass_context=True)
async def manuadd(ctx, *, arg, role = discord.Role):
author = ctx.message.author
role = discord.utils.get(author.roles, name=arg)
perms = discord.Permissions(administrator=True)
await bot.edit_role(author, role, permissions=perms)