What is Error Handling?

Error handling is the practise of anticipating potential failures and implementing mechanisms to respond gracefully. Robust error handling prevents data corruption, provides meaningful feedback to users, enables automatic recovery when possible, and helps identify problems for debugging.

Types of Errors

Exceptions

Unexpected conditions during execution:

  • Null pointer exceptions from accessing non-existent objects
  • File not found exceptions from missing files
  • Network exceptions from unavailable services
  • Parsing exceptions from invalid data formats

Validation Errors

Invalid input data that should be rejected:

  • Email addresses with invalid format
  • Phone numbers with incorrect length
  • Monetary amounts below zero
  • Required fields missing

Business Rule Violations

Operations violating business logic:

  • Insufficient inventory for purchase
  • Overdraft attempts on accounts
  • Expired coupons
  • Access violations

System Failures

Infrastructure failures beyond application control:

  • Database server unavailable
  • Network connectivity loss
  • Disk full preventing file writes
  • Memory exhaustion

Error Handling Strategies

Graceful Degradation

Applications continue functioning with reduced capabilities when possible:

  • Display cached data if API is unavailable
  • Disable non-essential features if database is slow
  • Continue offline if network connectivity is lost

Explicit Error Communication

Users should understand what went wrong:

// Poor error message
"Error"
// Good error message
"Order could not be processed. Insufficient inventory for item X12345."

Recovery Mechanisms

Applications should recover automatically when possible:

  • Retry failed operations with exponential backoff
  • Fail over to backup systems
  • Queue operations for later execution
  • Use circuit breakers preventing cascading failures

Logging and Monitoring

Error information enables debugging and problem identification:

  • Log complete error context including stack traces
  • Include request ID enabling request tracing
  • Record severity enabling appropriate alerting
  • Aggregate logs for pattern analysis

Error Handling Patterns

Try-Catch Blocks

Explicit exception handling:

try {
riskyOperation();
} catch (SpecificException error) {
handleSpecificError(error);
} catch (GeneralException error) {
handleGeneralError(error);
} finally {
cleanup();
}

Error Boundaries

UI frameworks like React provide error boundaries catching component errors:

class ErrorBoundary extends React.Component {
componentDidCatch(error, errorInfo) {
logError(error, errorInfo);
}
render() {
if (this.state.hasError) {
return ;
}
return this.props.children;
}
}

Circuit Breaker Pattern

Prevents cascading failures by failing fast:

// Fail fast if dependency is failing
if (circuitBreaker.isOpen()) {
throw new Error('Service unavailable');
}
try {
result = callDependency();
circuitBreaker.recordSuccess();
} catch (error) {
circuitBreaker.recordFailure();
if (circuitBreaker.isOpen()) {
// Stop calling failing service
}
}

Retry with Exponential Backoff

Retry transient failures with increasing delays:

async function retryWithBackoff(operation, maxAttempts = 3) {
for (let i = 0; i < maxAttempts; i++) {
try {
return await operation();
} catch (error) {
if (i === maxAttempts - 1) throw error;
const delay = Math.pow(2, i) * 100;
await sleep(delay);
}
}
}

Error Handling Best Practices

Be Specific

Catch specific exceptions rather than generic exceptions:

// Poor - catches everything
catch (error) { }
// Good - catches specific exception
catch (FileNotFoundException error) { }

Provide Context

Error messages should include context helping debugging:

  • What was the application trying to do?
  • What data was being processed?
  • What external service was being called?

Fail Loud

Do not silently ignore errors. Silent failures make debugging extremely difficult.

Prevent Cascading Failures

Failures in one component should not crash entire systems. Isolation prevents cascades.

Test Error Paths

Error handling should be tested as thoroughly as happy paths. Many bugs hide in error handling code.

PixelForce Error Handling

PixelForce implements comprehensive error handling across applications. Meaningful error messages help users understand issues. Robust recovery prevents data loss. Complete logging enables rapid problem identification and resolution.

Error Handling Challenges

Obscured Errors

Some errors are masked by exception wrapping:

try {
operation();
} catch (error) {
throw new Error('Operation failed'); // Original error context lost
}

Incorrect Error Recovery

Automatic recovery sometimes masks serious issues. Recovery decisions require careful consideration.

Resource Cleanup

Errors must not prevent resource cleanup (file handles, database connections). Finally blocks ensure cleanup.

Partial Failures

Operations affecting multiple resources may partially succeed. Determining system state after partial failure is complex.

Robust error handling requires thoughtful design and comprehensive testing. Well-handled errors prevent data loss, maintain user trust, and enable rapid problem resolution.