fix: Prevent errors during access to property of undefined object.

[Amoyaw-Curtis]

Context

init.ts:127 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'tier')
    at init (init.ts:127:1)
    at async initDemo (initDemo.js:11:1)
    at async initializeDicomViewer (cornerstone3D.tsx:13:1)

Changes & Results

Added optional chaining to resolve the issue of access to property of undefined object.

Before:

After:

Testing

Checklist

PR

• [] My Pull Request title is descriptive, accurate and follows the
  semantic-release format and guidelines.

Code

• [] My code has been well-documented (function documentation, inline comments,
  etc.)

• [] I have run the yarn build:update-api to update the API documentation, and have
  committed the changes to this PR. (Read more here https://www.cornerstonejs.org/docs/contribute/update-api)

Public Documentation Updates

• [] The documentation page has been updated as necessary for any public API
  additions or removals.

Tested Environment

• [] "OS: Windows 10
• [] "Node version: 20.10.0
• [] "Browser: Chrome Version 120.0.6099.109 (Official Build) (64-bit)

[netlify]

✅ Deploy Preview for cornerstone-3d-docs ready!

Name	Link
🔨 Latest commit	1c49649
🔍 Latest deploy log	https://app.netlify.com/sites/cornerstone-3d-docs/deploys/6580fbc749ae8c0008c5125e
😎 Deploy Preview	https://deploy-preview-955--cornerstone-3d-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.