fix(chatbot): closed session should not block bot re-activation

When a chatbot session exists with status='closed', the emit() method
returned early, preventing the bot from re-activating on new messages.

Root cause: the guard 'if (session.status === closed) return' was meant
to skip sessions not awaiting user input, but it also prevented new
conversations from starting after a bot flow completed.

Fix: nullify the session instead of returning, so processBot enters the
'!session' branch and creates a fresh session.

Also adds null guards:
- getConversationMessage: return empty string instead of undefined
- findBotByTrigger: handle null/undefined content gracefully

src/api/integrations/chatbot/base-chatbot.controller.ts

@@ -797,7 +797,7 @@ export abstract class BaseChatbotController<BotType = any, BotData extends BaseC
 
       if (this.checkIgnoreJids(settings?.ignoreJids, remoteJid)) return;
 
-      const session = await this.getSession(remoteJid, instance);
+      let session = await this.getSession(remoteJid, instance);
 
       const content = getConversationMessage(msg);
 
@@ -896,9 +896,9 @@ export abstract class BaseChatbotController<BotType = any, BotData extends BaseC
         return;
       }
 
-      // Skip if session exists but not awaiting user input
+      // If session is closed, nullify it so processBot creates a new conversation
       if (session && session.status === 'closed') {
-        return;
+        session = null;
       }
 
       // Merged settings

src/utils/findBotByTrigger.ts

@@ -1,6 +1,8 @@
 import { advancedOperatorsSearch } from './advancedOperatorsSearch';
 
 export const findBotByTrigger = async (botRepository: any, content: string, instanceId: string) => {
+  const normalizedContent = content?.trim() || '';
+
   // Check for triggerType 'all' or 'none' (both should match any message)
   const findTriggerAllOrNone = await botRepository.findFirst({
     where: {
@@ -16,6 +18,12 @@ export const findBotByTrigger = async (botRepository: any, content: string, inst
     return findTriggerAllOrNone;
   }
 
+  // If content is empty (null, undefined, whitespace-only, or media-only messages),
+  // only 'all'/'none' triggers apply — skip keyword/regex matching
+  if (!normalizedContent) {
+    return null;
+  }
+
   const findTriggerAdvanced = await botRepository.findMany({
     where: {
       enabled: true,

src/utils/getConversationMessage.ts

@@ -76,5 +76,5 @@ export const getConversationMessage = (msg: any) => {
 
   const messageContent = getMessageContent(types);
 
-  return messageContent;
+  return messageContent ?? '';
 };