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]

The latest updates on your projects. Learn more about Vercel for GitHub.

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

[almeidx]

Personally, I think this is a step in the right direction. However, I don't think this change alone is enough, as it will potentially bring different issues. For instance, passing an empty string to RoleManager#fetch() will now make a request to the Get Guild Roles endpoint, but through the Get Guild Role path internally. This will mean the endpoint will return a different body than expected, which might create worse errors that are harder to pinpoint.

To fix that, we should make further changes here. For instance, modifying the resolveId() method of managers to return null for empty strings. This solves the issue I mentioned in most places, but there are still some places that do not make use of this method (e.g., the RoleManager), so those places would have to be modified to make use of it.

[WhatCats]

For instance, passing an empty string to RoleManager#fetch() will now make a request to the Get Guild Roles endpoint, but through the Get Guild Role path internally.

I think I understand so the original idea was that you would query the empty string with Discord but your saying since the endpoint is /guild_id/roles/role_id if you pass an empty string it would result in /guild_id/roles/ which is a different endpoint.

Side Note: This makes me think the REST package shouldn't allow empty strings so you don't accidentally call a different endpoint.

To fix that, we should make further changes here. For instance, modifying the resolveId() method of managers to return null for empty strings.

I did consider this but then you would still end up explicitly calling the fetch-all endpoint for empty strings which is a problem as I originally described.

I'm thinking maybe it would make sense to throw a Discord like error for empty strings manually (like you would get if you passed any other non-snowflake string to the API because we can't actually pass the empty string because it would be interpreted as a different endpoint).

[almeidx]

I'm thinking maybe it would make sense to throw a Discord like error for empty strings manually (like you would get if you passed any other non-snowflake string to the API because we can't actually pass the empty string because it would be interpreted as a different endpoint).

We could throw an error in resolveId() if the input is a primitive value that is not a non-empty string