fix: standardize error classes in shared service modules

Replace raw `Error` with `UserError` for user-facing conditions (invalid trade state, user not found, permission/channel type checks) and `SystemError` for internal failures (DB insert failures, external API errors, missing config). Improves Discord UX by ensuring user-facing errors are surfaced cleanly via withCommandErrorHandling.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

shared/modules/economy/economy.service.ts

@@ -96,7 +96,7 @@ export const economyService = {
             });
 
             if (!user) {
-                throw new Error("User not found");
+                throw new UserError("User not found");
             }
 
             let streak = (user.dailyStreak || 0) + 1;

shared/modules/economy/exam.service.ts

@@ -4,7 +4,7 @@ import { TimerType, TransactionType } from "@shared/lib/constants";
 import { config } from "@shared/lib/config";
 import { withTransaction } from "@/lib/db";
 import type { Transaction } from "@shared/lib/types";
-import { UserError } from "@shared/lib/errors";
+import { UserError, SystemError } from "@shared/lib/errors";
 
 const EXAM_TIMER_TYPE = TimerType.EXAM_SYSTEM;
 const EXAM_TIMER_KEY = 'default';
@@ -86,7 +86,7 @@ export const examService = {
             // Ensure user exists
             const { userService } = await import("@shared/modules/user/user.service");
             const user = await userService.getOrCreateUser(userId, username, txFn);
-            if (!user) throw new Error("Failed to get or create user.");
+            if (!user) throw new SystemError("Failed to get or create user.");
 
             const now = new Date();
             const currentDay = now.getDay();
@@ -126,7 +126,7 @@ export const examService = {
                 where: eq(users.id, BigInt(userId))
             });
 
-            if (!user) throw new Error("User not found");
+            if (!user) throw new UserError("User not found");
 
             const timer = await txFn.query.userTimers.findFirst({
                 where: and(

shared/modules/game-settings/game-settings.service.ts

@@ -1,6 +1,7 @@
 import { eq } from "drizzle-orm";
 import { gameSettings } from "@db/schema";
 import { DrizzleClient } from "@shared/db/DrizzleClient";
+import { SystemError } from "@shared/lib/errors";
 import type {
     LevelingConfig,
     EconomyConfig,
@@ -88,7 +89,7 @@ export const gameSettingsService = {
         const existing = await gameSettingsService.getSettings(false);
 
         if (!existing) {
-            throw new Error("Game settings not found. Initialize settings first.");
+            throw new SystemError("Game settings not found. Initialize settings first.");
         }
 
         const updates: Partial<GameSettingsData> = { [section]: value };
@@ -101,7 +102,7 @@ export const gameSettingsService = {
         const settings = await gameSettingsService.getSettings(false);
 
         if (!settings) {
-            throw new Error("Game settings not found. Initialize settings first.");
+            throw new SystemError("Game settings not found. Initialize settings first.");
         }
 
         const commands = {

shared/modules/leveling/leveling.service.ts

@@ -4,6 +4,7 @@ import { withTransaction } from "@/lib/db";
 import { config } from "@shared/lib/config";
 import type { Transaction } from "@shared/lib/types";
 import { TimerKey, TimerType } from "@shared/lib/constants";
+import { UserError } from "@shared/lib/errors";
 
 export const levelingService = {
     // Calculate total XP required to REACH a specific level (Cumulative)
@@ -49,7 +50,7 @@ export const levelingService = {
                 where: eq(users.id, BigInt(id)),
             });
 
-            if (!user) throw new Error("User not found");
+            if (!user) throw new UserError("User not found");
 
             const currentXp = user.xp ?? 0n;
             const newXp = currentXp + amount;

shared/modules/moderation/moderation.service.ts

@@ -4,6 +4,7 @@ import { DrizzleClient } from "@shared/db/DrizzleClient";
 import type { CreateCaseOptions, ClearCaseOptions, SearchCasesFilter } from "@/modules/moderation/moderation.types";
 import { getUserWarningEmbed } from "@/modules/moderation/moderation.view";
 import { CaseType } from "@shared/lib/constants";
+import { SystemError } from "@shared/lib/errors";
 
 export interface ModerationCaseConfig {
     dmOnWarn?: boolean;
@@ -100,7 +101,7 @@ export const moderationService = {
         });
 
         if (!moderationCase) {
-            throw new Error("Failed to create moderation case");
+            throw new SystemError("Failed to create moderation case");
         }
 
         const warningCount = await getActiveWarningCount(options.userId);

shared/modules/moderation/prune.service.ts

@@ -2,6 +2,7 @@ import { Collection, Message, PermissionFlagsBits } from "discord.js";
 import type { TextBasedChannel } from "discord.js";
 import type { PruneOptions, PruneResult, PruneProgress } from "@/modules/moderation/prune.types";
 import { config } from "@shared/lib/config";
+import { UserError, SystemError } from "@shared/lib/errors";
 
 /**
  * Fetch messages from a channel
@@ -30,7 +31,7 @@ async function processBatch(
     userId?: string
 ): Promise<{ deleted: number; skipped: number }> {
     if (!('bulkDelete' in channel)) {
-        throw new Error("This channel type does not support bulk deletion");
+        throw new UserError("This channel type does not support bulk deletion");
     }
 
     // Filter by user if specified
@@ -54,7 +55,7 @@ async function processBatch(
         };
     } catch (error) {
         console.error("Error during bulk delete:", error);
-        throw new Error("Failed to delete messages");
+        throw new SystemError("Failed to delete messages");
     }
 }
 
@@ -76,12 +77,12 @@ export const pruneService = {
     ): Promise<PruneResult> {
         // Validate channel permissions
         if (!('permissionsFor' in channel)) {
-            throw new Error("Cannot check permissions for this channel type");
+            throw new UserError("Cannot check permissions for this channel type");
         }
 
         const permissions = channel.permissionsFor(channel.client.user!);
         if (!permissions?.has(PermissionFlagsBits.ManageMessages)) {
-            throw new Error("Missing permission to manage messages in this channel");
+            throw new UserError("Missing permission to manage messages in this channel");
         }
 
         const { amount, userId, all } = options;

shared/modules/trade/trade.service.ts

@@ -5,6 +5,7 @@ import { itemTransactions } from "@db/schema";
 import { withTransaction } from "@/lib/db";
 import type { Transaction } from "@shared/lib/types";
 import { TransactionType, ItemTransactionType } from "@shared/lib/constants";
+import { UserError } from "@shared/lib/errors";
 
 // Module-level session storage
 const sessions = new Map<string, TradeSession>();
@@ -114,11 +115,11 @@ export const tradeService = {
      */
     updateMoney: (threadId: string, userId: string, amount: bigint) => {
         const session = tradeService.getSession(threadId);
-        if (!session) throw new Error("Session not found");
+        if (!session) throw new UserError("Session not found");
-        if (session.state !== 'NEGOTIATING') throw new Error("Trade is not active");
+        if (session.state !== 'NEGOTIATING') throw new UserError("Trade is not active");
 
         const participant = session.userA.id === userId ? session.userA : session.userB.id === userId ? session.userB : null;
-        if (!participant) throw new Error("User not in trade");
+        if (!participant) throw new UserError("User not in trade");
 
         participant.offer.money = amount;
         unlockAll(session);
@@ -127,11 +128,11 @@ export const tradeService = {
 
     addItem: (threadId: string, userId: string, item: { id: number, name: string }, quantity: bigint) => {
         const session = tradeService.getSession(threadId);
-        if (!session) throw new Error("Session not found");
+        if (!session) throw new UserError("Session not found");
-        if (session.state !== 'NEGOTIATING') throw new Error("Trade is not active");
+        if (session.state !== 'NEGOTIATING') throw new UserError("Trade is not active");
 
         const participant = session.userA.id === userId ? session.userA : session.userB.id === userId ? session.userB : null;
-        if (!participant) throw new Error("User not in trade");
+        if (!participant) throw new UserError("User not in trade");
 
         const existing = participant.offer.items.find(i => i.id === item.id);
         if (existing) {
@@ -146,10 +147,10 @@ export const tradeService = {
 
     removeItem: (threadId: string, userId: string, itemId: number) => {
         const session = tradeService.getSession(threadId);
-        if (!session) throw new Error("Session not found");
+        if (!session) throw new UserError("Session not found");
 
         const participant = session.userA.id === userId ? session.userA : session.userB.id === userId ? session.userB : null;
-        if (!participant) throw new Error("User not in trade");
+        if (!participant) throw new UserError("User not in trade");
 
         participant.offer.items = participant.offer.items.filter(i => i.id !== itemId);
 
@@ -159,10 +160,10 @@ export const tradeService = {
 
     toggleLock: (threadId: string, userId: string): boolean => {
         const session = tradeService.getSession(threadId);
-        if (!session) throw new Error("Session not found");
+        if (!session) throw new UserError("Session not found");
 
         const participant = session.userA.id === userId ? session.userA : session.userB.id === userId ? session.userB : null;
-        if (!participant) throw new Error("User not in trade");
+        if (!participant) throw new UserError("User not in trade");
 
         participant.locked = !participant.locked;
         session.lastInteraction = Date.now();
@@ -179,10 +180,10 @@ export const tradeService = {
      */
     executeTrade: async (threadId: string): Promise<void> => {
         const session = tradeService.getSession(threadId);
-        if (!session) throw new Error("Session not found");
+        if (!session) throw new UserError("Session not found");
 
         if (!session.userA.locked || !session.userB.locked) {
-            throw new Error("Both players must accept the trade first.");
+            throw new UserError("Both players must accept the trade first.");
         }
 
         session.state = 'COMPLETED'; // Prevent double execution

shared/modules/trivia/trivia.service.ts

@@ -3,7 +3,7 @@ import { eq, and, sql } from "drizzle-orm";
 import { config } from "@shared/lib/config";
 import { withTransaction } from "@/lib/db";
 import type { Transaction } from "@shared/lib/types";
-import { UserError } from "@shared/lib/errors";
+import { UserError, SystemError } from "@shared/lib/errors";
 import { TimerType, TransactionType } from "@shared/lib/constants";
 import { DrizzleClient } from "@shared/db/DrizzleClient";
 
@@ -94,13 +94,13 @@ class TriviaService {
             const data = await response.json() as OpenTDBResponse;
 
             if (data.response_code !== 0 || !data.results || data.results.length === 0) {
-                throw new Error('Failed to fetch trivia question');
+                throw new SystemError('Failed to fetch trivia question');
             }
 
             const result = data.results[0];
 
             if (!result) {
-                throw new Error('No trivia question returned');
+                throw new SystemError('No trivia question returned');
             }
 
             // Decode base64