Discord.js: messageReactionAdd malfunction

[dorianxonic]

Please describe the problem you are having in as much detail as possible:
When listening for messageReactionAdd (with raw emitter for the uncached message) console returns TypeError.

Include a reproducible code sample here, if possible:

// Case 1 using  .emoji
client.on('messageReactionAdd', (messageReaction, user) => {
    console.log(messageReaction.emoji.name)
});
/* TypeError: Cannot read property 'name' of undefined
    at Client.client.on (C:\Users\viks\Desktop\basil\basil.js:79:36)
    at Client.emit (events.js:198:13)
    at reactionChannel.fetchMessage.then.msg (C:\Users\viks\Desktop\basil\basil.js:70:13)
    at process._tickCallback (internal/process/next_tick.js:68:7) */
//-----------------------------------------------------------------------------------------
// Case 2 using ._emoji
client.on('messageReactionAdd', (messageReaction, user) => {
    console.log(messageReaction._emoji.name)
});
/*  TypeError: Cannot read property 'name' of undefined
    at Client.client.on (C:\Users\viks\Desktop\basil\basil.js:79:37)
    at Client.emit (events.js:198:13)
    at reactionChannel.fetchMessage.then.msg (C:\Users\viks\Desktop\basil\basil.js:70:13)
    at process._tickCallback (internal/process/next_tick.js:68:7) */

• When using .last() I encounter this:
  Case 1: Stock unicode emojis...

client.on('messageReactionAdd', (messageReaction, user) => {
    console.log(messageReaction.last()._emoji)
});

...to which console returns:

ReactionEmoji {
  reaction:
   MessageReaction {
     message:
      Message {
        channel: [TextChannel],
        deleted: false,
        id: '589443774401216526',
        type: 'DEFAULT',
        content:
         'he limpiado 5 mensajes por orden de: <@262388004675387393> �' ,
        author: [ClientUser],
        member: [GuildMember],
        pinned: false,
        tts: false,
        nonce: undefined,
        system: false,
        embeds: [],
        attachments: Collection [Map] {},
        createdTimestamp: 1560604747153,
        editedTimestamp: null,
        reactions: [Collection],
        mentions: [MessageMentions],
        webhookID: null,
        hit: null,
        _edits: [] },
     me: false,
     count: 1,
     users: Collection [Map] {},
     _emoji: [Circular] },
  name: '�',
  id: null }

But gives a...

console.log(messageReaction.last()._emoji)
                            ^

TypeError: messageReaction.last is not a function

...when using a custom emoji.
Case 2: custom emojis...

client.on('messageReactionAdd', (messageReaction, user) => {
    console.log(messageReaction.last().emoji)
});

... to which console returns:

Emoji {
  guild:
   Guild {
     members:
      Collection [Map] {
        '231217147869790208' => [GuildMember],
        '246781870606516225' => [GuildMember],
        '262388004675387393' => [GuildMember],
        '325654156075335680' => [GuildMember],
        '588289543162036246' => [GuildMember],
        '588584416142426112' => [GuildMember] },
     channels:
      Collection [Map] {
        '587404335961342082' => [VoiceChannel],
        '587905715574800385' => [TextChannel],
        '587915270052642816' => [TextChannel],
        '588818158526136331' => [TextChannel],
        '588893876870316053' => [TextChannel],
        '588984749721124874' => [TextChannel],
        '589383100874752010' => [CategoryChannel],
        '589383117077348352' => [TextChannel],
        '589383129324584970' => [TextChannel],
        '589383140741480458' => [TextChannel] },
     roles:
      Collection [Map] {
        '587404335281995786' => [Role],
        '587825294644346883' => [Role],
        '588289992678440960' => [Role],
        '588712471028826125' => [Role],
        '589383217447174144' => [Role],
        '589383260396847124' => [Role],
        '589383317732851712' => [Role] },
     presences:
      Collection [Map] {
        '231217147869790208' => [Presence],
        '262388004675387393' => [Presence],
        '588289543162036246' => [Presence],
        '588584416142426112' => [Presence] },
     deleted: false,
     available: true,
     id: '587404335281995786',
     name: 'Basil Dev',
     icon: '8abc385497fa17230e7c8530ce4fb680',
     splash: null,
     region: 'eu-west',
     memberCount: 6,
     large: false,
     features: [],
     applicationID: null,
     afkTimeout: 300,
     afkChannelID: null,
     systemChannelID: null,
     embedEnabled: undefined,
     verificationLevel: 0,
     explicitContentFilter: 0,
     mfaLevel: 0,
     joinedTimestamp: 1560329664145,
     defaultMessageNotifications: 'MENTIONS',
     ownerID: '262388004675387393',
     _rawVoiceStates: Collection [Map] {},
     emojis: Collection [Map] { '589413200735240195' => [Circular] } },
  deleted: false,
  id: '589413200735240195',
  name: 'twitch',
  requiresColons: true,
  managed: false,
  animated: false,
  _roles: [] }

But gives a...

console.log(messageReaction.last().emoji)
                            ^

TypeError: messageReaction.last is not a function

...when using stock unicode emojis.

Further details:

• discord.js version: 11.5.1
• Node.js version: 10.16.0
• Operating system: Windows 10 x64
• Priority this issue should have – please be realistic and elaborate if possible:
  Medium. This bug might break many reaction-role type of bots.

• [ ] I have also tested the issue on latest master, commit hash:

[SpaceEEC]

Several things

Firstly (and importantly in this issue)

(with raw emitter for the uncached message)

If you are coming from the [guide], you should have seen the big warning there, stating that this is undocumented and _unsupported_. (If not, now you know)

In that case, you should rather open an issue there. (Although you should provide the exact code you use in your raw handler)

If this is your own implementation, I suggest to only use the raw event without messing with discord.js private api any further. (For example: Emit your own events using only the raw data, if that is works to you.)

This whole headache luckily gets fixed with [partials] on master / v12.

Secondly (and only as a note)

messageReaction._emoji

This is a private property you do neither have a reason to nor should use.
If you look at the source of MessageReaction#emoji, you see that the getter, in case of a ReactionEmoji, is checking for a newly available Emoji and falls back to _emoji if none was found.

This has nothing to do with your issue though.

Lastly

messageReaction.last()

MessageReaction has no method called last.
It is representing a single reaction, not several.

Since this is working for you in same cases, I am going to suspect you emit something incorrect.

[dorianxonic]

Thanks for the detailed answer. Yes, I was emitting something wrong indeed... my bad.