Fix User Parameter Validation and SVG Error Handling

[armanpanigrahi59]

Description

Fixes #870

Pillar

• 🎨 Pillar 1 — New Theme Design
• 📐 Pillar 2 — Geometric SVG Improvement
• 🕐 Pillar 3 — Timezone Logic Optimization
• 🛠️ Other (Bug fix, refactoring, docs)

Visual Preview

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file.
• I have tested these changes locally (localhost:3000/api/streak?user=YOUR_USERNAME).
• I have run npm run format and npm run lint locally and resolved all errors (CI will fail otherwise).
• My commits follow the Conventional Commits format (e.g., feat(themes): ..., fix(calculate): ...).
• I have updated README.md if I added a new theme or URL parameter.
• I have started the repo.
• I have made sure that i have only one commit to merge in this PR.
• The SVG output matches the CommitPulse "premium quality" aesthetic standard (no raw elements, smooth animations, correct fonts).
• (Recommended) I joined the CommitPulse Discord community for contributor discussions, mentorship, and faster PR support.

[vercel]

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[retenta-bot]

This PR improves user parameter validation and error handling for SVGs, which is crucial for maintaining a smooth user experience. It aligns with previous decisions to enhance visual elements and user interactions, such as the addition of a dark/light preview background toggle and language-aware visualizations. Thank you for your contributions, and I look forward to your updates!

[github-actions]

📦 Next.js Bundle Size Report (Gzipped Sizes)

Asset	PR Size	Base Size	Difference	Status
static/chunks/3952-[hash].js	7.84 KB	7.80 KB	+0.04 KB (+0.54%)	🔴 Regression

📊 Summary of Totals

Category	PR Size	Base Size	Difference
Total JS	5005.27 KB	5005.04 KB	+0.22 KB (+0.00%)
Total CSS	354.80 KB	354.80 KB	0 B

[Aamod007]

The error handling and validation fix for JSON responses is good, but your branch is polluted with unrelated commits (like the Docker builds, timezone mocks, and webhook handler changes). Could you please rebase your branch or isolate just the SVG/JSON error handling changes into a clean branch? We can't merge this while it contains unrelated commits from other PRs.