fix: Prevent inbox settings freeze on empty welcome_tagline (#12440)

# Pull Request Template

## Description

Fixes #12419 

## Type of change

Please delete options that are not relevant.

- [x] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide
instructions so we can reproduce. Please also list any relevant details
for your test configuration.

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/javascript/dashboard/routes/dashboard/settings/inbox/Settings.vue

@@ -328,7 +328,7 @@ export default {
         this.continuityViaEmail = this.inbox.continuity_via_email;
         this.channelWebsiteUrl = this.inbox.website_url;
         this.channelWelcomeTitle = this.inbox.welcome_title;
-        this.channelWelcomeTagline = this.inbox.welcome_tagline;
+        this.channelWelcomeTagline = this.inbox.welcome_tagline || '';
         this.selectedFeatureFlags = this.inbox.selected_feature_flags || [];
         this.replyTime = this.inbox.reply_time;
         this.locktoSingleConversation = this.inbox.lock_to_single_conversation;