checking if the user is in the server before creating the trade

ballsdex/packages/trade/cog.py

@@ -107,6 +107,7 @@ async def begin(self, interaction: discord.Interaction["BallsDexBot"], user: dis
         user: discord.User
             The user you want to trade with
         """
+        guild = cast(discord.Guild, interaction.guild)
         if user.bot:
             await interaction.response.send_message("You cannot trade with bots.", ephemeral=True)
             return
@@ -115,6 +116,11 @@ async def begin(self, interaction: discord.Interaction["BallsDexBot"], user: dis
                 "You cannot trade with yourself.", ephemeral=True
             )
             return
+        if guild.get_member(user.id) is None:
+            await interaction.response.send_message(
+                "You cannot trade with a user that is not in the server.", ephemeral=True
+            )
+            return
 
         trade1, trader1 = self.get_trade(interaction)
         trade2, trader2 = self.get_trade(channel=interaction.channel, user=user)  # type: ignore