fix: Do not allow sending messages if merged contact has a duplicate session (#11152)

In this PR https://github.com/chatwoot/chatwoot/pull/11139, if there is
an attempt to create a duplication session for the contact in the same
inbox, we will anonymize the old session.

This PR would prevent sending messages to the older sessions. The
support agents will have to create a new conversation to continue
messages with customer.

app/controllers/api/v1/accounts/contacts/contact_inboxes_controller.rb

@@ -9,6 +9,8 @@ class Api::V1::Accounts::Contacts::ContactInboxesController < Api::V1::Accounts:
       source_id: params[:source_id],
       hmac_verified: hmac_verified?
     ).perform
+  rescue ArgumentError => e
+    render json: { error: e.message }, status: :unprocessable_entity
   end
 
   private