diff --git a/bot/core/module.py b/bot/core/module.py
index e46f9875..daaa4bc7 100644
--- a/bot/core/module.py
+++ b/bot/core/module.py
@@ -46,11 +46,12 @@ async def preload_guild_configuration(client):
     Loads the plain guild configuration for all guilds the client is part of into data.
     """
     guildids = [guild.id for guild in client.guilds]
-    rows = client.data.guild_config.fetch_rows_where(guildid=guildids)
-    client.log(
-        "Preloaded guild configuration for {} guilds.".format(len(rows)),
-        context="CORE_LOADING"
-    )
+    if guildids:
+        rows = client.data.guild_config.fetch_rows_where(guildid=guildids)
+        client.log(
+            "Preloaded guild configuration for {} guilds.".format(len(rows)),
+            context="CORE_LOADING"
+        )
 
 
 @module.launch_task
@@ -59,11 +60,12 @@ async def preload_studying_members(client):
     Loads the member data for all members who are currently in voice channels.
     """
     userids = list(set(member.id for guild in client.guilds for ch in guild.voice_channels for member in ch.members))
-    rows = client.data.lions.fetch_rows_where(userid=userids)
-    client.log(
-        "Preloaded member data for {} members.".format(len(rows)),
-        context="CORE_LOADING"
-    )
+    if userids:
+        rows = client.data.lions.fetch_rows_where(userid=userids)
+        client.log(
+            "Preloaded member data for {} members.".format(len(rows)),
+            context="CORE_LOADING"
+        )
 
 
 @module.launch_task
diff --git a/bot/modules/accountability/TimeSlot.py b/bot/modules/accountability/TimeSlot.py
index 8fc178f3..b87a0df3 100644
--- a/bot/modules/accountability/TimeSlot.py
+++ b/bot/modules/accountability/TimeSlot.py
@@ -72,6 +72,9 @@ class TimeSlot:
         connect=False
     )
 
+    happy_lion = "https://media.discordapp.net/stickers/898266283559227422.png"
+    sad_lion = "https://media.discordapp.net/stickers/898266548421148723.png"
+
     def __init__(self, guild, start_time, data=None):
         self.guild: discord.Guild = guild
         self.start_time: datetime.datetime = start_time
@@ -139,13 +142,16 @@ class TimeSlot:
                 else:
                     classifications["Attended"].append(mention)
 
+            all_attended = all(mem.has_attended for mem in self.members.values())
             bonus_line = (
-                "{tick} All members attended, and will get a `{bonus} LC` completion bonus!".format(
+                "{tick} Everyone attended, and will get a `{bonus} LC` bonus!".format(
                     tick=tick,
                     bonus=GuildSettings(self.guild.id).accountability_bonus.value
                 )
-                if all(mem.has_attended for mem in self.members.values()) else ""
+                if all_attended else ""
             )
+            if all_attended:
+                embed.set_thumbnail(url=self.happy_lion)
 
             embed.description += "\n" + bonus_line
             for field, value in classifications.items():
@@ -182,16 +188,22 @@ class TimeSlot:
                 else:
                     classifications["Missing"].append(mention)
 
+            all_attended = all(mem.has_attended for mem in self.members.values())
+
             bonus_line = (
-                "{tick} All members attended, and received a `{bonus} LC` completion bonus!".format(
+                "{tick} Everyone attended, and received a `{bonus} LC` bonus!".format(
                     tick=tick,
                     bonus=GuildSettings(self.guild.id).accountability_bonus.value
                 )
-                if all(mem.has_attended for mem in self.members.values()) else
+                if all_attended else
                 "{cross} Some members missed the session, so everyone missed out on the bonus!".format(
                     cross=cross
                 )
             )
+            if all_attended:
+                embed.set_thumbnail(url=self.happy_lion)
+            else:
+                embed.set_thumbnail(url=self.sad_lion)
 
             embed.description += "\n" + bonus_line
             for field, value in classifications.items():
@@ -292,7 +304,7 @@ class TimeSlot:
                 self.message = await self.lobby.send(
                     embed=self.open_embed
                 )
-            except discord.HTTPException as e:
+            except discord.HTTPException:
                 GuildSettings(self.guild.id).event_log.log(
                     "Failed to post the status message in the accountability lobby {}.\n"
                     "Skipping this session.".format(self.lobby.mention),
@@ -322,10 +334,21 @@ class TimeSlot:
         Update the status message, and launch the DM reminder.
         """
         if self.channel:
-            await self.channel.edit(name="Accountability Study Room")
-            await self.channel.set_permissions(self.guild.default_role, view_channel=True, connect=False)
+            try:
+                await self.channel.edit(name="Accountability Study Room")
+                await self.channel.set_permissions(self.guild.default_role, view_channel=True, connect=False)
+            except discord.HTTPException:
+                pass
             asyncio.create_task(self.dm_reminder(delay=60))
-        await self.message.edit(embed=self.status_embed)
+        try:
+            await self.message.edit(embed=self.status_embed)
+        except discord.NotFound:
+            try:
+                self.message = await self.lobby.send(
+                    embed=self.status_embed
+                )
+            except discord.HTTPException:
+                self.message = None
 
     async def dm_reminder(self, delay=60):
         """
diff --git a/bot/modules/accountability/tracker.py b/bot/modules/accountability/tracker.py
index e1136b39..51713230 100644
--- a/bot/modules/accountability/tracker.py
+++ b/bot/modules/accountability/tracker.py
@@ -232,7 +232,8 @@ async def turnover():
 
     # Start all the current rooms
     await asyncio.gather(
-        *(slot.start() for slot in current_slots)
+        *(slot.start() for slot in current_slots),
+        return_exceptions=True
     )
 
 
diff --git a/bot/modules/moderation/tickets/Ticket.py b/bot/modules/moderation/tickets/Ticket.py
index 3193a185..4d7ec5ec 100644
--- a/bot/modules/moderation/tickets/Ticket.py
+++ b/bot/modules/moderation/tickets/Ticket.py
@@ -353,9 +353,10 @@ class Ticket:
         Method used to revert the ticket action, e.g. unban or remove mute role.
         Generally called by `pardon` and `_expire`.
 
-        Must be overriden by the Ticket type, if they implement any revert logic.
+        May be overriden by the Ticket type, if they implement any revert logic.
+        Is a no-op by default.
         """
-        raise NotImplementedError
+        return
 
     async def _expire(self):
         """
diff --git a/bot/modules/moderation/video/admin.py b/bot/modules/moderation/video/admin.py
index fd75573b..1f0ddaab 100644
--- a/bot/modules/moderation/video/admin.py
+++ b/bot/modules/moderation/video/admin.py
@@ -87,9 +87,9 @@ class video_studyban(settings.Boolean, GuildSetting):
     @property
     def success_response(self):
         if self.value:
-            "Members will now be study banned if they don't enable their video in the configured video channels."
+            return "Members will now be study-banned if they don't enable their video in the configured video channels."
         else:
-            "Members will not be studybanned if they don't enable their video in video channels."
+            return "Members will not be study-banned if they don't enable their video in video channels."
 
 
 @GuildSettings.attach_setting
diff --git a/bot/modules/study/studybadge_cmd.py b/bot/modules/study/studybadge_cmd.py
index b43dae4b..99e28fec 100644
--- a/bot/modules/study/studybadge_cmd.py
+++ b/bot/modules/study/studybadge_cmd.py
@@ -265,6 +265,13 @@ async def cmd_studybadges(ctx, flags):
         # Parse the input
         lines = ctx.args.splitlines()
         results = [await parse_level(ctx, line) for line in lines]
+        # Check for duplicates
+        _set = set()
+        duplicate = next((time for time, _ in results if time in _set or _set.add(time)), None)
+        if duplicate:
+            return await ctx.error_reply(
+                "Level `{}` provided twice!".format(strfdur(duplicate, short=False))
+            )
         current_times = set(row.required_time for row in guild_roles)
 
         # Split up the provided lines into levels to add and levels to edit
diff --git a/bot/settings/setting_types.py b/bot/settings/setting_types.py
index 89b1b0a6..25a63faa 100644
--- a/bot/settings/setting_types.py
+++ b/bot/settings/setting_types.py
@@ -1,6 +1,5 @@
 import json
 import asyncio
-import datetime
 import itertools
 from io import StringIO
 from enum import IntEnum
@@ -12,7 +11,7 @@ from cmdClient.Context import Context
 from cmdClient.lib import SafeCancellation
 
 from meta import client
-from utils.lib import parse_dur, strfdur, strfdelta, prop_tabulate, multiple_replace
+from utils.lib import parse_dur, strfdur, prop_tabulate, multiple_replace
 
 from .base import UserInputError
 
@@ -100,7 +99,7 @@ class Boolean(SettingType):
         Looks up the provided string in the truthy and falsey tables.
         """
         _userstr = userstr.lower()
-        if _userstr == "none":
+        if not _userstr or _userstr == "none":
             return None
         if _userstr in cls._truthy:
             return True
@@ -154,7 +153,7 @@ class Integer(SettingType):
         """
         Relies on integer casting to convert the user string
         """
-        if userstr.lower() == "none":
+        if not userstr or userstr.lower() == "none":
             return None
 
         try:
@@ -222,7 +221,7 @@ class String(SettingType):
         Check that the user-entered string is of the correct length.
         Accept "None" to unset.
         """
-        if userstr.lower() == "none":
+        if not userstr or userstr.lower() == "none":
             # Unsetting case
             return None
         elif cls._maxlen is not None and len(userstr) > cls._maxlen:
@@ -284,7 +283,7 @@ class Channel(SettingType):
         Pass to the channel seeker utility to find the requested channel.
         Handle `0` and variants of `None` to unset.
         """
-        if userstr.lower() in ('0', 'none'):
+        if userstr.lower() in ('', '0', 'none'):
             return None
         else:
             channel = await ctx.find_channel(userstr, interactive=True, chan_type=cls._chan_type)
@@ -296,13 +295,17 @@ class Channel(SettingType):
     @classmethod
     def _format_data(cls, id: int, data: Optional[int], **kwargs):
         """
-        Retrieve an artificially created channel mention.
-        If the channel does not exist, this will show up as invalid-channel.
+        Retrieve the channel mention, if the channel still exists.
+        If the channel no longer exists, or cannot be seen by the client, returns None.
         """
         if data is None:
             return None
         else:
-            return "<#{}>".format(data)
+            channel = client.get_channel(data)
+            if channel:
+                return channel.mention
+            else:
+                return None
 
 
 class VoiceChannel(Channel):
@@ -375,7 +378,7 @@ class Role(SettingType):
         Pass to the role seeker utility to find the requested role.
         Handle `0` and variants of `None` to unset.
         """
-        if userstr.lower() in ('0', 'none'):
+        if userstr.lower() in ('', '0', 'none'):
             return None
         else:
             role = await ctx.find_role(userstr, create=cls._parse_create, interactive=True)
@@ -452,7 +455,7 @@ class Emoji(SettingType):
         Pass to the emoji string parser to get the emoji.
         Handle `0` and variants of `None` to unset.
         """
-        if userstr.lower() in ('0', 'none'):
+        if userstr.lower() in ('', '0', 'none'):
             return None
         else:
             return cls._parse_emoji(userstr)
@@ -505,7 +508,7 @@ class Timezone(SettingType):
         Check that the user-entered string is of the correct length.
         Accept "None" to unset.
         """
-        if userstr.lower() == "none":
+        if not userstr or userstr.lower() == "none":
             # Unsetting case
             return None
         try:
@@ -585,7 +588,7 @@ class IntegerEnum(SettingType):
 
         options = {name.lower(): mem.value for name, mem in cls._enum.__members__.items()}
 
-        if userstr == "none":
+        if not userstr or userstr == "none":
             # Unsetting case
             return None
         elif userstr not in options:
@@ -654,7 +657,7 @@ class Duration(SettingType):
         """
         Parse the provided duration.
         """
-        if userstr.lower() == "none":
+        if not userstr or userstr.lower() == "none":
             return None
 
         if cls._default_multiplier and userstr.isdigit():
@@ -949,12 +952,13 @@ class SettingList(SettingType):
         Splits the user string across `,` to break up the list.
         Handle `0` and variants of `None` to unset.
         """
-        if userstr.lower() in ('0', 'none'):
+        if userstr.lower() in ('', '0', 'none'):
             return []
         else:
             data = []
-            for item in userstr.split(','):
-                data.append(await cls._setting._parse_userstr(ctx, id, item.strip()))
+            items = (item.strip() for item in userstr.split(','))
+            items = (item for item in items if item)
+            data = [await cls._setting._parse_userstr(ctx, id, item, **kwargs) for item in items]
 
             if cls._force_unique:
                 data = list(set(data))