chore: Rescue slack link unfurling errors. (#11033)

Fixes
https://linear.app/chatwoot/issue/CW-4122/slackwebapierrorsmissingscope-missing-scope

This PR adds the ability to handle errors when scopes are missing during
link unfurling. Since link unfurling is just a nice-to-have feature that
doesn't affect core functionality, we will silently ignore these errors.

---------

Co-authored-by: Sojan <sojan@pepalo.com>

lib/integrations/slack/send_on_slack_service.rb

@@ -18,6 +18,10 @@ class Integrations::Slack::SendOnSlackService < Base::SendOnChannelService
     slack_client.chat_unfurl(
       event
     )
+    # You may wonder why we're not requesting reauthorization and disabling hooks when scope errors occur.
+    # Since link unfurling is just a nice-to-have feature that doesn't affect core functionality, we will silently ignore these errors.
+  rescue Slack::Web::Api::Errors::MissingScope => e
+    Rails.logger.warn "Slack: Missing scope error: #{e.message}"
   end
 
   private

spec/lib/integrations/slack/send_on_slack_service_spec.rb

@@ -269,6 +269,19 @@ describe Integrations::Slack::SendOnSlackService do
         expect(hook).to be_disabled
         expect(hook).to have_received(:prompt_reauthorization!)
       end
+
+      it 'logs MissingScope error during link unfurl' do
+        unflur_payload = { channel: 'channel', ts: 'timestamp', unfurls: {} }
+        error = Slack::Web::Api::Errors::MissingScope.new('Missing required scope')
+
+        expect(slack_client).to receive(:chat_unfurl)
+          .with(unflur_payload)
+          .and_raise(error)
+
+        expect(Rails.logger).to receive(:warn).with('Slack: Missing scope error: Missing required scope')
+
+        link_builder.link_unfurl(unflur_payload)
+      end
     end
 
     context 'when message contains mentions' do