Message.deletable giving TypeError (possible issue with Channel.permissionsFor)

[iamtraction]

Please describe the problem you are having in as much detail as possible:

Message.deletable sometimes gives TypeError: Cannot read property 'has' of null.
Upon looking at the discord.js code for Message.deletable, I found that the actual issue is with Channel.permissionsFor() - it sometimes returns null (check the complete stack trace below):

get deletable() {
  return this.author.id === this.client.user.id || (this.guild &&
    this.channel.permissionsFor(this.client.user).has(Permissions.FLAGS.MANAGE_MESSAGES)
  );
}

I've previously found that Channel.permissionsFor() returned null sometimes, but I thought that was intended. So, I did a workaround for that when I directly accessed that. But if Message.deletable internally uses that and it gives a TypeError, that's a bug and should be fixed. And so, I'm reporting it.

Include a reproducible code sample here, if possible:

if (msg.deletable) { // L48 - This is the line causing the TypeError.
  msg.delete().catch(e => {
    Bastion.log.error(e);
  });
}

Link to the snippet above: https://github.com/TheBastionBot/Bastion/blob/master/modules/games/acrophobia.js#L48

Complete stack trace of the error:

TypeError: Cannot read property 'has' of null
    at Message.get deletable [as deletable] (/some/directory/Bastion/node_modules/discord.js/src/structures/Message.js:323:52)
    at MessageCollector.collector.on (/some/directory/Bastion/modules/games/acrophobia.js:48:17)
    at emitTwo (events.js:131:20)
    at MessageCollector.emit (events.js:214:7)
    at MessageCollector._handle (/some/directory/Bastion/node_modules/discord.js/src/structures/interfaces/Collector.js:92:10)
    at emitOne (events.js:121:20)
    at Client.emit (events.js:211:7)
    at MessageCreateHandler.handle (/some/directory/Bastion/node_modules/discord.js/src/client/websocket/packets/handlers/MessageCreate.js:9:34)
    at WebSocketPacketManager.handle (/some/directory/Bastion/node_modules/discord.js/src/client/websocket/packets/WebSocketPacketManager.js:103:65)
    at WebSocketConnection.onPacket (/some/directory/Bastion/node_modules/discord.js/src/client/websocket/WebSocketConnection.js:330:35)
    at WebSocketConnection.onMessage (/some/directory/Bastion/node_modules/discord.js/src/client/websocket/WebSocketConnection.js:293:17)
    at WebSocket.onMessage (/some/directory/Bastion/node_modules/ws/lib/event-target.js:120:16)
    at emitOne (events.js:116:13)
    at WebSocket.emit (events.js:211:7)
    at Receiver._receiver.onmessage (/some/directory/Bastion/node_modules/ws/lib/websocket.js:145:47)
    at Receiver.dataMessage (/some/directory/Bastion/node_modules/ws/lib/receiver.js:430:14)
    at Receiver.getData (/some/directory/Bastion/node_modules/ws/lib/receiver.js:368:12)
    at Receiver.startLoop (/some/directory/Bastion/node_modules/ws/lib/receiver.js:164:16)
    at Receiver.add (/some/directory/Bastion/node_modules/ws/lib/receiver.js:138:10)
    at TLSSocket._ultron.on (/some/directory/Bastion/node_modules/ws/lib/websocket.js:143:54)
    at emitOne (events.js:116:13)
    at TLSSocket.emit (events.js:211:7)
Trace
    at Object.exports.error.message [as error] (/some/directory/Bastion/handlers/logHandler.js:31:11)
    at MessageCollector.collector.on (/some/directory/Bastion/modules/games/acrophobia.js:69:21)
    at emitTwo (events.js:131:20)
    at MessageCollector.emit (events.js:214:7)
    at MessageCollector._handle (/some/directory/Bastion/node_modules/discord.js/src/structures/interfaces/Collector.js:92:10)
    at emitOne (events.js:121:20)
    at Client.emit (events.js:211:7)
    at MessageCreateHandler.handle (/some/directory/Bastion/node_modules/discord.js/src/client/websocket/packets/handlers/MessageCreate.js:9:34)
    at WebSocketPacketManager.handle (/some/directory/Bastion/node_modules/discord.js/src/client/websocket/packets/WebSocketPacketManager.js:103:65)
    at WebSocketConnection.onPacket (/some/directory/Bastion/node_modules/discord.js/src/client/websocket/WebSocketConnection.js:330:35)
    at WebSocketConnection.onMessage (/some/directory/Bastion/node_modules/discord.js/src/client/websocket/WebSocketConnection.js:293:17)
    at WebSocket.onMessage (/some/directory/Bastion/node_modules/ws/lib/event-target.js:120:16)
    at emitOne (events.js:116:13)
    at WebSocket.emit (events.js:211:7)
    at Receiver._receiver.onmessage (/some/directory/Bastion/node_modules/ws/lib/websocket.js:145:47)
    at Receiver.dataMessage (/some/directory/Bastion/node_modules/ws/lib/receiver.js:430:14)
    at Receiver.getData (/some/directory/Bastion/node_modules/ws/lib/receiver.js:368:12)
    at Receiver.startLoop (/some/directory/Bastion/node_modules/ws/lib/receiver.js:164:16)
    at Receiver.add (/some/directory/Bastion/node_modules/ws/lib/receiver.js:138:10)
    at TLSSocket._ultron.on (/some/directory/Bastion/node_modules/ws/lib/websocket.js:143:54)
    at emitOne (events.js:116:13)
    at TLSSocket.emit (events.js:211:7)

Further details:

• discord.js version: 11.3.0
• node.js version: 8.9.4
• Operating system: Debian 9.1 x64
• Priority this issue should have – please be realistic and elaborate if possible:
  Medium - Because it doesn't happen all the time. I've got 6 logs of this error since last Sunday.

• I found this issue while running code on a user account
• I have also tested the issue on latest master, commit hash:

[SpaceEEC]

I backported #2026 with 3df3741, which would fix your issue if the cause is the bot leaving and rejoining a guild.
This is probably not the only cause of the own member being uncached as you can read up in #1870.

If you have any idea on reproducing this feel free to let me know.

[iamtraction]

No, the cause isn't related to bot leaving and rejoining a guild (at least not for me).

I don't know of any way of reproducing this. It looks like it happens at random. I run the bot continuously for a week until it's updated and restarted, and when I check the logs for previous week this comes up in the logs. I don't see any specific pattern, so I am unable to reproduce it.

[iamtraction]

dc92582 probably fixed it as I haven't encountered this issue after updating to discord.js v11.3.2. So, I'm closing this issue. Thanks for the fix!