Returning a better exception type

cogs/killstream.py

@@ -229,7 +229,7 @@ class Killstream(commands.Cog):
 
     async def process_entity_criteria(self, ctx, entity_type, entity_name, value):
         if entity_type not in ['character', 'corporation', 'alliance']:
-            raise ValueError('Invalid entity!')
+            raise commands.BadArgument('Invalid entity!')
 
         try:
             entity_lookup = await self.bot.esi.search(entity_type, entity_name)