Fixes
https://linear.app/chatwoot/issue/CW-6358/handling-of-nil-conversation-in-the-readstatusservice
Improve handling of nil conversation in the `ReadStatusService` to
prevent potential errors. Ensure that the conversation is checked before
performing updates to message status. This change fixes the below error.
```
NoMethodError: undefined method 'conversations' for nil (NoMethodError)
channel.inbox.contact_inboxes.find_by(source_id: tt_conversation_id).conversations.first
^^^^^^^^^^^^^^
from app/services/tiktok/messaging_helpers.rb:29:in 'Tiktok::MessagingHelpers#find_conversation'
from app/services/tiktok/read_status_service.rb:13:in 'Tiktok::ReadStatusService#conversation'
from app/services/tiktok/read_status_service.rb:9:in 'Tiktok::ReadStatusService#perform'
from app/jobs/webhooks/tiktok_events_job.rb:67:in 'Webhooks::TiktokEventsJob#im_mark_read_msg'
from app/jobs/webhooks/tiktok_events_job.rb:31:in 'Webhooks::TiktokEventsJob#process_event'
from app/jobs/webhooks/tiktok_events_job.rb:15:in 'block in Webhooks::TiktokEventsJob#perform'
from app/jobs/mutex_application_job.rb:23:in 'MutexApplicationJob#with_lock'
from app/jobs/webhooks/tiktok_events_job.rb:14:in 'Webhooks::TiktokEventsJob#perform'
from activejob (7.1.5.2) lib/active_job/execution.rb:68:in 'block in ActiveJob::Execution#_perform_job'
from activesupport (7.1.5.2) lib/active_support/callbacks.rb:121:in 'block in ActiveSupport::Callbacks#run_callbacks'
from i18n (1.14.7) lib/i18n.rb:353:in 'I18n::Base#with_locale'
from activejob (7.1.5.2) lib/active_job/translation.rb:9:in 'block (2 levels) in <module:Translation>'
from activesupport (7.1.5.2) lib/active_support/callbacks.rb:130:in 'BasicObject#instance_exec'
from activesupport (7.1.5.2) lib/active_support/callbacks.rb:130:in 'block in ActiveSupport::Callbacks#run_callbacks'
from activesupport (7.1.5.2) lib/active_support/core_ext/time/zones.rb:65:in 'Time.use_zone'
from activejob (7.1.5.2) lib/active_job/timezones.rb:9:in 'block (2 levels) in <module:Timezones>'
from activesupport (7.1.5.2) lib/active_support/callbacks.rb:130:in 'BasicObject#instance_exec'
from activesupport (7.1.5.2) lib/active_support/callbacks.rb:130:in 'block in ActiveSupport::Callbacks#run_callbacks'
from activesupport (7.1.5.2) lib/active_support/callbacks.rb:141:in 'ActiveSupport::Callbacks#run_callbacks'
from activejob (7.1.5.2) lib/active_job/execution.rb:67:in 'ActiveJob::Execution#_perform_job
```
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
40c622ed95