merge: fix(ui): restore ThemeSelector and add error resilience testing (#8042)

## Description

Fixes #6888

This PR addresses the issue where `ThemeSelector` was causing an
"Element type is invalid: expected a string... but got: undefined"
crash. The component file was accidentally overwritten during previous
testing. This PR restores the component implementation and adds a
dedicated error resilience test suite
(`ThemeSelector.error-resilience.test.tsx`) to guarantee the component
renders gracefully even with invalid props, undefined themes, or
unhandled child exceptions. It also resolves a merge conflict in
`route.ts`.

## Pillar

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

## Visual Preview

*(No visual changes, fixes a crash)*

## Checklist before requesting a review:

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

Author: JhaSourav07

app/api/student/resume/upload/route.mock-integrations.test.ts

@@ -131,3 +131,150 @@ describe('API Route: Student Resume Upload (Mock Integrations)', () => {
     expect(parseResume).not.toHaveBeenCalled();
   });
 });
+
+// 1. Mock the External Modules and Service Layers
+vi.mock('@/utils/getClientIp', () => ({
+  getClientIp: vi.fn(() => '127.0.0.1'),
+}));
+
+vi.mock('@/lib/rate-limit', () => {
+  const RateLimiterMock = vi.fn();
+  RateLimiterMock.prototype.check = vi.fn().mockResolvedValue(true);
+  RateLimiterMock.prototype.checkWithResult = vi
+    .fn()
+    .mockResolvedValue({ success: true, limit: 10, remaining: 9, reset: 0 });
+  return {
+    RateLimiter: RateLimiterMock,
+    getRateLimitHeaders: vi.fn().mockReturnValue(new Headers()),
+  };
+});
+
+vi.mock('@/lib/resume-parser', () => ({
+  parseResume: vi.fn(),
+  hasValidFileSignature: vi.fn().mockReturnValue(true),
+  ALLOWED_MIME_TYPES: [
+    'application/pdf',
+    'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+  ],
+  MAX_FILE_SIZE: 5 * 1024 * 1024, // 5MB
+}));
+
+describe('API Route: Student Resume Upload (Mock Integrations)', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  // THE FIX: Explicitly mock formData() to bypass Vitest parsing issues
+  const createMockRequest = (
+    fileName = 'resume.pdf',
+    fileType = 'application/pdf',
+    fieldName = 'resume'
+  ) => {
+    const formData = new FormData();
+    const file = new File(['dummy pdf buffer content'], fileName, { type: fileType });
+    if (fieldName) formData.append(fieldName, file);
+
+    const req = new Request('http://localhost/api/student/resume/upload', {
+      method: 'POST',
+      // We don't attach the body here to avoid parsing crashes
+    });
+
+    // We force the request to resolve our formData object when asked
+    req.formData = vi.fn().mockResolvedValue(formData) as unknown as () => Promise<FormData>;
+
+    return req;
+  };
+
+  it('1. should test service loading paths to ensure successful parsing returns 200 (mock success)', async () => {
+    // Arrange: Mock the async service to succeed
+    const mockParsedData = {
+      name: 'Priyanuj',
+      email: 'test@example.com',
+      phone: '1234567890',
+      skills: ['React', 'Next.js'],
+      education: [],
+      experience: [],
+    };
+    vi.mocked(parseResume).mockResolvedValueOnce(mockParsedData);
+
+    const req = createMockRequest();
+
+    // Act
+    const res = await POST(req);
+    const json = await res.json();
+
+    // Assert
+    expect(res.status).toBe(200);
+    expect(json.success).toBe(true);
+    expect(json.data).toEqual(mockParsedData);
+    expect(parseResume).toHaveBeenCalledTimes(1);
+  });
+
+  it('2. should assert local cache layers (RateLimiter) block requests before triggering async services', async () => {
+    // Arrange: Mock the RateLimiter cache to block the user
+    vi.mocked(RateLimiter.prototype.checkWithResult).mockResolvedValueOnce({
+      success: false,
+      limit: 10,
+      remaining: 0,
+      reset: 0,
+    });
+
+    const req = createMockRequest();
+
+    // Act
+    const res = await POST(req);
+    const json = await res.json();
+
+    // Assert: Blocked with 429, and parseResume is NEVER called
+    expect(res.status).toBe(429);
+    expect(json.error).toMatch(/Too many requests/i);
+    expect(parseResume).not.toHaveBeenCalled();
+  });
+
+  it('3. should verify correct fallback procedures during fake endpoint/parsing errors', async () => {
+    // Arrange: Simulate the PDF parser crashing or timing out
+    vi.mocked(parseResume).mockRejectedValueOnce(new Error('Parser timeout'));
+
+    const req = createMockRequest();
+
+    // Act
+    const res = await POST(req);
+    const json = await res.json();
+
+    // Assert: Route catches the error safely and returns 422
+    expect(res.status).toBe(422);
+    expect(json.success).toBe(false);
+    expect(json.error).toMatch(/Failed to parse resume/i);
+  });
+
+  it('4. should block invalid file signatures without hitting the parser service', async () => {
+    // Arrange: Simulate a user renaming a .exe file to .pdf
+    vi.mocked(hasValidFileSignature).mockReturnValueOnce(false);
+
+    const req = createMockRequest();
+
+    // Act
+    const res = await POST(req);
+    const json = await res.json();
+
+    // Assert: Fails security check (400) before reaching the async parser
+    expect(res.status).toBe(400);
+    expect(json.error).toMatch(/File content does not match its type/i);
+    expect(parseResume).not.toHaveBeenCalled();
+  });
+
+  it('5. should reject requests with missing formData fields without processing', async () => {
+    // Arrange: Send a request where the file is named 'wrong_field' instead of 'resume'
+    const req = createMockRequest('test.pdf', 'application/pdf', 'wrong_field_name');
+
+    // Act
+    const res = await POST(req);
+    const json = await res.json();
+
+    // Assert: Immediately fails validation (400)
+    expect(res.status).toBe(400);
+    expect(json.error).toMatch(/No resume file provided/i);
+    expect(RateLimiter.prototype.checkWithResult).toHaveBeenCalled();
+    expect(parseResume).not.toHaveBeenCalled();
+  });
+});

app/customize/components/ThemeSelector.error-resilience.test.tsx

@@ -0,0 +1,93 @@
+import React from 'react';
+import { render, screen } from '@testing-library/react';
+import { describe, it, expect, vi } from 'vitest';
+import { ThemeSelector } from './ThemeSelector';
+
+// 1. MOCK ALL DEPENDENCIES FULLY
+vi.mock('./ThemeQuickPresets', () => ({
+  ThemeQuickPresets: () => <div data-testid="mock-presets">Presets</div>,
+}));
+
+vi.mock('./SectionLabel', () => ({
+  SectionLabel: ({ children }: { children: React.ReactNode }) => <div>{children}</div>,
+}));
+
+vi.mock('../../../lib/svg/themes', () => ({
+  themes: {
+    dracula: { bg: '000', accent: '000', text: '000' },
+    neon: { bg: '000', accent: '000', text: '000' },
+    ocean: { bg: '000', accent: '000', text: '000' },
+    sunset: { bg: '000', accent: '000', text: '000' },
+    light: { bg: '000', accent: '000', text: '000' },
+    dark: { bg: '000', accent: '000', text: '000' },
+  },
+}));
+
+vi.mock('../types', () => ({
+  THEME_KEYS: ['dracula', 'neon', 'ocean', 'sunset', 'auto', 'random'],
+}));
+
+// 2. Error Boundary
+class TestErrorBoundary extends React.Component<
+  { children: React.ReactNode },
+  { hasError: boolean }
+> {
+  constructor(props: { children: React.ReactNode }) {
+    super(props);
+    this.state = { hasError: false };
+  }
+  static getDerivedStateFromError() {
+    return { hasError: true };
+  }
+  render() {
+    if (this.state.hasError) return <div data-testid="error-fallback">Error</div>;
+    return this.props.children;
+  }
+}
+
+describe('ThemeSelector Resilience', () => {
+  it('should render successfully with a valid theme', () => {
+    render(
+      <TestErrorBoundary>
+        <ThemeSelector theme="dracula" onThemeChange={vi.fn()} />
+      </TestErrorBoundary>
+    );
+    expect(screen.getByRole('combobox')).toBeInTheDocument();
+    expect(screen.queryByTestId('error-fallback')).not.toBeInTheDocument();
+  });
+
+  it('should handle invalid theme strings gracefully without crashing', () => {
+    // This tests if the component handles bad inputs without throwing exceptions
+    render(
+      <TestErrorBoundary>
+        <ThemeSelector theme="not-a-real-theme" onThemeChange={vi.fn()} />
+      </TestErrorBoundary>
+    );
+    expect(screen.queryByTestId('error-fallback')).not.toBeInTheDocument();
+  });
+
+  it('should render gracefully with undefined theme prop', () => {
+    render(
+      <TestErrorBoundary>
+        <ThemeSelector theme={undefined as unknown as string} onThemeChange={vi.fn()} />
+      </TestErrorBoundary>
+    );
+    expect(screen.queryByTestId('error-fallback')).not.toBeInTheDocument();
+  });
+
+  it('should catch crashes in children via Error Boundary', () => {
+    // Force a child component to crash
+    const CrashingChild = () => {
+      throw new Error('Crash');
+    };
+
+    render(
+      <TestErrorBoundary>
+        <ThemeSelector theme="dracula" onThemeChange={vi.fn()} />
+        <CrashingChild />
+      </TestErrorBoundary>
+    );
+
+    expect(screen.getByTestId('error-fallback')).toBeInTheDocument();
+  });
+});

app/generator/components/SectionCard.error-resilience.test.tsx

@@ -117,10 +117,10 @@ describe('SectionCard Error Resilience', () => {
     );
 
     expect(telemetrySpy).toHaveBeenCalledTimes(1);
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+
     const [errorArg] = telemetrySpy.mock.calls[0];
     expect(errorArg).toBeInstanceOf(Error);
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+
     expect((errorArg as Error).message).toBe('Standard runtime exception');
 
     consoleErrorSpy.mockRestore();