Fix Guild#welcomeScreen handling (#1150)

Author: bit0r1n

lib/structures/Guild.js

@@ -264,10 +264,10 @@ class Guild extends Base {
         if(data.max_video_channel_users !== undefined) {
             this.maxVideoChannelUsers = data.max_video_channel_users;
         }
-        if(data.guild.welcome_screen !== undefined) {
+        if(data.welcome_screen !== undefined) {
             this.welcomeScreen = {
-                description: data.guild.welcome_screen.description,
-                welcomeChannels: data.guild.welcome_screen.welcome_channels && data.guild.welcome_screen.welcome_channels.map((c) => {
+                description: data.welcome_screen.description,
+                welcomeChannels: data.welcome_screen.welcome_channels && data.welcome_screen.welcome_channels.map((c) => {
                     return {
                         channelID: c.channel,
                         description: c.description,