fix: typing mismatch for empty strings being treated as undefined

[WhatCats]

Problem

At the moment methods like GuildMemberManager:fetch that have an optional string parameter are doing a falsy check for if the parameter was omitted. But consider the following typescript code:

const id: string = ""
const member: GuildMember = await guild.members.fetch(id)

According to the typings member should be a GuildMember but its actually a Collection<Snowflake, GuildMember> because the empty string is falsy (this is why we love JS).

My Suggestion

Do more exact undefined/null checks.
(I might not have found every place this is an issue)

[vercel]

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2 Skipped Deployments

Project	Deployment	Preview	Comments	Updated (UTC)
discord-js	Skipped			Nov 20, 2025 10:44pm
discord-js-guide	Skipped			Nov 20, 2025 10:44pm