Fixed welcome and leave channel commands.

cogs/moderation.py

@@ -205,7 +205,10 @@ class Moderation(commands.Cog):
                 mycursor.execute(sql, val)
                 mydb.commit()
                 await ctx.send(f'Set new welcome.channel as {channel.mention}.')
-
+        else:
+            if channel == None:
+                await ctx.send("You need to specify the channel.")
+                return
             else:
                 sql = "INSERT INTO welcomech (chid, serverid) VALUES (%s, %s)"
                 val = (channel.id, ctx.guild.id)
@@ -311,6 +314,10 @@ class Moderation(commands.Cog):
                 mycursor.execute(sql, val)
                 mydb.commit()
                 await ctx.send(f'Setting new leave channel as {channel.mention}.')
+        else:
+            if channel == None:
+                await ctx.send("You need to specify the channel.")
+                return
             else:
                 sql = "INSERT INTO leavech (chid, serverid) VALUES (%s, %s)"
                 val = (channel.id, ctx.guild.id)