fix: guard against malformed/non-array history data in fetchUserInfo

[Tamcodes4]

Description

Fixes a crash in fetch-user-info.js when historical user data is malformed. The endpoint now gracefully falls back to an empty history array instead of throwing an error when the fetched JSON is null or contains a non-array history field.

Linked Issue

Fixes #239

Changes Made

• Added a null/object check before accessing migrated profile fields.
• Added a defensive Array.isArray(history) guard before sorting historical data.
• Preserved the existing migration logic for both legacy array-based and new object-based profile formats.
• Prevented history.sort() from throwing when malformed history data is encountered.

Type of Change

• Bug fix
• New feature
• UI/Visual update
• Documentation update
• Refactor

Testing

• Tested locally
• Tested on mobile viewport (if applicable)
• No console errors introduced

Test Cases

Verified the following scenarios locally:

• Valid legacy history array
• Valid object-based profile structure
• Empty object ({})
• null
• { "history": "corrupted" }
• { "history": {} }

Confirmed that malformed history data now degrades gracefully to an empty history array instead of causing the /api/user/:username endpoint to fail.

Checklist

• My code follows the project's coding style
• I have formatted my code locally by running npx prettier --write . before submitting
• I am submitting my PR from a dedicated feature/* branch, not the main branch
• I have performed a self-review of my code
• My changes generate no new warnings or errors
• I have updated documentation if required
• I have linked the relevant issue

Screenshots / Screen Recording

N/A, Backend robustness fix with no UI changes.

[github-actions]

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[Tamcodes4]

Hey @jagdish-15, could you review this pr?