refactor: modularize events.js and add missing tests

src/modules/events/errors.js

@@ -0,0 +1,40 @@
+/**
+ * Error Event Handlers
+ * Handles Discord client errors and process-level error handling
+ */
+
+import { Events } from 'discord.js';
+import { error as logError } from '../../logger.js';
+
+/** @type {boolean} Guard against duplicate process-level handler registration */
+let processHandlersRegistered = false;
+
+/**
+ * Register error event handlers
+ * @param {Client} client - Discord client
+ */
+export function registerErrorHandlers(client) {
+  client.on(Events.Error, (err) => {
+    logError('Discord error', { error: err.message, stack: err.stack });
+  });
+
+  if (!processHandlersRegistered) {
+    process.on('unhandledRejection', (err) => {
+      logError('Unhandled rejection', { error: err?.message || String(err), stack: err?.stack });
+    });
+    process.on('uncaughtException', async (err) => {
+      logError('Uncaught exception — shutting down', {
+        error: err?.message || String(err),
+        stack: err?.stack,
+      });
+      try {
+        const { Sentry } = await import('../../sentry.js');
+        await Sentry.flush(2000);
+      } catch {
+        // ignore — best-effort flush
+      }
+      process.exit(1);
+    });
+    processHandlersRegistered = true;
+  }
+}

src/modules/events/guildMemberAdd.js

@@ -0,0 +1,20 @@
+/**
+ * Guild Member Add Event Handler
+ * Handles welcome messages when users join a guild
+ */
+
+import { Events } from 'discord.js';
+import { getConfig } from '../config.js';
+import { sendWelcomeMessage } from '../welcome.js';
+
+/**
+ * Register a handler that sends the configured welcome message when a user joins a guild.
+ * @param {Client} client - Discord client instance to attach the event listener to.
+ * @param {Object} _config - Unused (kept for API compatibility); handler resolves per-guild config via getConfig().
+ */
+export function registerGuildMemberAddHandler(client, _config) {
+  client.on(Events.GuildMemberAdd, async (member) => {
+    const guildConfig = getConfig(member.guild.id);
+    await sendWelcomeMessage(member, client, guildConfig);
+  });
+}