feat: Add user existence checks to economy commands and refactor trade service to expose sessions for testing.

src/commands/economy/pay.ts

@@ -33,6 +33,11 @@ export const pay = createCommand({
 
         const amount = BigInt(interaction.options.getInteger("amount", true));
         const senderId = interaction.user.id;
+        if (!targetUser) {
+            await interaction.reply({ embeds: [createErrorEmbed("User not found.")], flags: MessageFlags.Ephemeral });
+            return;
+        }
+
         const receiverId = targetUser.id;
 
         if (amount < config.economy.transfers.minAmount) {
@@ -40,14 +45,14 @@ export const pay = createCommand({
             return;
         }
 
-        if (senderId === receiverId) {
+        if (senderId === receiverId.toString()) {
             await interaction.reply({ embeds: [createErrorEmbed("You cannot pay yourself.")], flags: MessageFlags.Ephemeral });
             return;
         }
 
         try {
             await interaction.deferReply();
-            await economyService.transfer(senderId, receiverId, amount);
+            await economyService.transfer(senderId, receiverId.toString(), amount);
 
             const embed = createSuccessEmbed(`Successfully sent ** ${amount}** Astral Units to <@${targetUser.id}>.`, "💸 Transfer Successful");
             await interaction.editReply({ embeds: [embed], content: `<@${receiverId}>` });