slideshare/ERROR_HANDLING_STANDARDS.md

Error Handling Standards

Current State: INCONSISTENT

Error handling varies across the codebase - some functions have comprehensive error handling while others are missing it entirely.

Required Error Handling Patterns

1. Error Boundaries (MISSING)

Implement React error boundaries for component-level error handling:

// ✅ IMPLEMENT - ThemeErrorBoundary.tsx
import React, { Component, ErrorInfo, ReactNode } from 'react';

interface Props {
  children: ReactNode;
  fallback?: ReactNode;
}

interface State {
  hasError: boolean;
  error?: Error;
}

export class ThemeErrorBoundary extends Component<Props, State> {
  constructor(props: Props) {
    super(props);
    this.state = { hasError: false };
  }

  static getDerivedStateFromError(error: Error): State {
    return { hasError: true, error };
  }

  componentDidCatch(error: Error, errorInfo: ErrorInfo) {
    console.error('Theme component error:', error, errorInfo);
    // Log to error reporting service in production
  }

  render() {
    if (this.state.hasError) {
      return this.props.fallback || (
        <div className="error-fallback">
          <h2>Something went wrong</h2>
          <p>There was an error loading the theme system.</p>
          <button onClick={() => window.location.reload()}>
            Reload Page
          </button>
        </div>
      );
    }

    return this.props.children;
  }
}

2. Async Error Handling (STANDARDIZE)

Consistent pattern for all async operations:

// ✅ STANDARD PATTERN
const performAsyncOperation = async (id: string) => {
  try {
    setLoading(true);
    setError(null);
    
    const result = await riskyOperation(id);
    
    if (!result) {
      throw new Error(`Operation failed for ${id}`);
    }
    
    return result;
  } catch (error) {
    const message = error instanceof Error ? error.message : 'Unknown error occurred';
    setError(message);
    console.error(`Async operation failed:`, error);
    throw error; // Re-throw if caller needs to handle
  } finally {
    setLoading(false);
  }
};

3. Hook Error Handling (IMPLEMENT)

Custom hook for consistent error states:

// ✅ IMPLEMENT - useAsyncOperation.ts
import { useState, useCallback } from 'react';

interface AsyncState<T> {
  data: T | null;
  loading: boolean;
  error: string | null;
}

export function useAsyncOperation<T>() {
  const [state, setState] = useState<AsyncState<T>>({
    data: null,
    loading: false,
    error: null
  });

  const execute = useCallback(async (operation: () => Promise<T>) => {
    setState(prev => ({ ...prev, loading: true, error: null }));
    
    try {
      const data = await operation();
      setState({ data, loading: false, error: null });
      return data;
    } catch (error) {
      const message = error instanceof Error ? error.message : 'Operation failed';
      setState(prev => ({ ...prev, loading: false, error: message }));
      throw error;
    }
  }, []);

  return { ...state, execute };
}

4. Network Error Handling (ENHANCE)

Standardized fetch error handling:

// ✅ STANDARD PATTERN
const fetchWithErrorHandling = async (url: string, options?: RequestInit) => {
  try {
    const response = await fetch(url, options);
    
    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`);
    }
    
    return response;
  } catch (error) {
    if (error instanceof TypeError) {
      throw new Error('Network error - check your connection');
    }
    throw error;
  }
};

Error Types & Classifications

1. User Errors (Recoverable)

• Invalid theme selection
• Missing form data
• File upload issues Handling: Show user-friendly message, allow retry

2. System Errors (Technical)

• Network failures
• Parse errors
• Configuration issues Handling: Log details, show generic message, provide fallback

3. Critical Errors (Unrecoverable)

• Dependency failures
• Memory issues
• Corrupt data Handling: Error boundary, full page reload option

Logging Standards

Development

// ✅ PATTERN
console.group(`🔥 ${operation} Error`);
console.error('Details:', error);
console.error('Context:', context);
console.groupEnd();

Production

// ✅ PATTERN (when error service added)
errorReportingService.captureException(error, {
  context,
  user: getCurrentUser(),
  timestamp: new Date().toISOString()
});

Error Message Standards

User-Facing Messages

• Clear & Actionable: "Could not load theme. Please try again."
• No technical jargon: Avoid error codes, stack traces
• Suggest solutions: "Check your connection and retry"

Developer Messages

• Detailed context: Include operation, parameters, state
• Stack traces: Preserve for debugging
• Structured data: Consistent error object format

Implementation Checklist

HIGH PRIORITY

• Add ThemeErrorBoundary to App.tsx
• Implement useAsyncOperation hook
• Standardize theme loading error handling
• Add network error handling to fetch operations

MEDIUM PRIORITY

• Create error fallback components
• Add error recovery mechanisms (retry buttons)
• Implement error state consistency across components
• Add loading state management standards

LOW PRIORITY

• Add error reporting service integration
• Implement error analytics tracking
• Add error rate monitoring
• Create error handling documentation

Testing Requirements

• Error boundary testing: Verify fallback rendering
• Async error testing: Test network failures, timeouts
• Recovery testing: Ensure retry mechanisms work
• Error state testing: Verify error messages display correctly

Current Problem Areas

Missing Error Boundaries

No React error boundaries implemented - component errors crash the app

Inconsistent Async Patterns

Some async operations handle errors, others don't:

• themeLoader.ts ✅ Has good error handling
• Some components ❌ Missing error handling

No Error Recovery

Users cannot recover from errors - no retry buttons or reload options

Logging Inconsistency

Mix of console.warn, console.error, and no logging