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

src/commands/economy/exam.ts

@@ -25,6 +25,10 @@ export const exam = createCommand({
     execute: async (interaction) => {
         await interaction.deferReply();
         const user = await userService.getOrCreateUser(interaction.user.id, interaction.user.username);
+        if (!user) {
+            await interaction.editReply({ embeds: [createErrorEmbed("Failed to retrieve user data.")] });
+            return;
+        }
         const now = new Date();
         const currentDay = now.getDay();
 
@@ -47,7 +51,7 @@ export const exam = createCommand({
 
                 const metadata: ExamMetadata = {
                     examDay: currentDay,
-                    lastXp: user.xp.toString()
+                    lastXp: (user.xp ?? 0n).toString()
                 };
 
                 await DrizzleClient.insert(userTimers).values({
@@ -98,7 +102,7 @@ export const exam = createCommand({
 
                 const newMetadata: ExamMetadata = {
                     examDay: examDay,
-                    lastXp: user.xp.toString() // Reset tracking
+                    lastXp: (user.xp ?? 0n).toString()
                 };
 
                 await DrizzleClient.update(userTimers)
@@ -125,7 +129,7 @@ export const exam = createCommand({
 
             // 5. Reward Calculation
             const lastXp = BigInt(metadata.lastXp || "0"); // Fallback just in case
-            const currentXp = user.xp;
+            const currentXp = user.xp ?? 0n;
             const diff = currentXp - lastXp;
 
             // Calculate Reward