guild.get_member_named() returns None for some users

[al-matty]

async def get_user_roles(self, discord_username, guild_id) -> list:
guild = await self.get_guild(guild_id)
user = guild.get_member_named(discord_username)
roles = [role.name for role in user.roles]

telegram_bot.py", line 202, in discord_roles
roles_available = await self.discord_bot.get_user_roles(discord_handle, guild_id)
discord_bot.py", line 139, in get_user_roles
roles = [role.name for role in user.roles]
AttributeError: 'NoneType' object has no attribute 'roles'

TODO's:
-Remove conversion to lowercase for Discord handles in Telegram menu. This leads to matching errors.