Requesting the `InviteUsersToConversation(..)` to return user details on failed calls

[kevinkowalew]

Description

As explained in the conversations.invite Usage info documentation including a single bad user ID in an conversations.invite request will cause all the invites to fail. In such cases, the API response includes an errors list containing user details as well as an error explaining the reason for each respective invite failure (as shown below).

{
    "ok": false,
    "error": "user_not_found",
    "errors": [
        {
            "user": "U111111",
            "ok": false,
            "error": "user_not_found"
        },
        {
            "user": "U222222",
            "ok": false,
            "error": "cant_invite_self"
        }
    ]
}

In the current state, the slack-go module doesn't expose any of these user details in the error value returned from the InviteUsersToConversation client method. It just solely returns the error value from the API response (ex: cant_invite, already_in_channel, etc):

slack/conversation.go

Line 322 in abcbf2b

func (api *Client) InviteUsersToConversation(channelID string, users ...string) (*Channel, error) {

This is problematic if you wish to implement a wrapper around the client which is resilient to such failures, as there is no easy way to determine which user IDs in your request caused the failure.

Potential Solution

One potential solution for this issue could be to use errors.Join to include additional errors with the relevant user details for each failure. I imagine there's some backwards compatibility concerns to consider for existing clients there, but nonetheless wanted to bring this issue to your attention. Thanks!