Fix private messages

extensions/help.py

@@ -1,6 +1,7 @@
 from discord import Embed
 from discord.ext import commands
-from discord.ext.commands import CommandNotFound, MissingRequiredArgument, BadArgument, MissingPermissions
+from discord.ext.commands import CommandNotFound, MissingRequiredArgument, BadArgument, MissingPermissions, \
+    NoPrivateMessage
 
 from administrator import config
 from administrator.logger import logger
@@ -14,7 +15,6 @@ logger = logger.getChild(extension_name)
 class Help(commands.Cog):
     def __init__(self, bot: commands.Bot):
         self.bot = bot
-        self.purges = {}
 
     @commands.command("help", pass_context=True)
     async def help(self, ctx: commands.Context):
@@ -48,7 +48,8 @@ class Help(commands.Cog):
             await ctx.message.add_reaction("\u2753")
         elif isinstance(error, MissingRequiredArgument) or isinstance(error, BadArgument):
             await ctx.message.add_reaction("\u274C")
-        elif isinstance(error, NotOwner) or isinstance(error, MissingPermissions):
+        elif isinstance(error, NotOwner) or isinstance(error, MissingPermissions)\
+                or isinstance(error, NoPrivateMessage):
             await ctx.message.add_reaction("\u274C")
         else:
             await ctx.send("An error occurred !")

extensions/presentation.py

@@ -58,6 +58,7 @@ class Presentation(commands.Cog):
 
     @commands.Cog.listener()
     async def on_message(self, message: Message):
+        if message.guild is not None:
             s = db.Session()
             p = s.query(db.Presentation).filter(db.Presentation.guild == message.guild.id).first()
             s.close()

extensions/purge.py

@@ -41,6 +41,7 @@ class Purge(commands.Cog):
 
     @commands.Cog.listener()
     async def on_raw_reaction_add(self, payload: RawReactionActionEvent):
+        if payload.guild_id:
             user = self.bot.get_user(payload.user_id)
             message = await self.bot.get_guild(payload.guild_id).get_channel(payload.channel_id)\
                 .fetch_message(payload.message_id)