SDK: Improve error message display for failed angular example authentication

[fmontes]

Problem Statement

When the angular example fails for authentication, it currently shows a blank screen, which does not provide any useful information to developers on how to resolve the issue.

Steps to Reproduce

Run the Angular example without info in the environtment file.

Acceptance Criteria

• [ ] When the angular example fails for authentication or no dotcms host selected, a clear error message should be displayed on the screen to guide developers on how to fix the issue.

External Links

• N/A

Assumptions & Initiation Needs

• The error message should be concise and informative, providing guidance on resolving authentication issues.
• Development team needs to implement the logic to display the error message when authentication fails.

Quality Assurance Notes & Workarounds

N/A