Prevent crash when FOOTER_SECTION.sections is undefined

[sancheet230]

Closes #262

Fixes:

1. Used optional chaining (?.) to safely access FOOTER_SECTION.sections
2. If sections is not available, it gracefully skips rendering the section

Changes

1. Updated CustomFooter to use:

{FOOTER_SECTION?.sections?.map((section) => ( ... ))}

2. Ensured the UI remains functional even if the footer JSON does not include sections

Testing

1. Verified the footer renders properly when FOOTER_SECTION.sections is defined.
2. Confirmed the component does not crash if FOOTER_SECTION.sections is missing or empty

Author Checklist

• Ensure you provide a DCO sign-off for your commits using the --signoff option of git commit.
• Vital features and changes captured in unit and/or integration tests
• Commits messages follow AP format
• Extend the documentation, if necessary
• Merging to main from fork:branchname

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[sancheet230]

@DianaLease There are new files created in the codebase when I was working on this issue so now I have to configure the codebase again for solving this issue according to new code changes. Will raise a new PR soon