Error Handling

The SDK throws structured error objects with error codes, suggestions, and documentation links. Every error extends ZendFiError and can be caught with standard try/catch.

Error Hierarchy

Error Properties

Every ZendFiError includes:

Property	Type	Description
`code`	`string`	Machine-readable error code
`type`	`string`	Error category
`message`	`string`	Human-readable description
`suggestion`	`string?`	Actionable fix recommendation
`docs_url`	`string`	Link to error documentation
`statusCode`	`number?`	HTTP status code (0 for network errors)
`response`	`unknown`	Raw API response body

Error Types

AuthenticationError

Thrown when the API key is invalid, expired, or revoked.

try {
  await zendfi.createPayment({ amount: 10 });
} catch (error) {
  if (error instanceof AuthenticationError) {
    // error.code: 'authentication_failed'
    // error.statusCode: 401
    // error.suggestion: 'Check your API key in the dashboard...'
    console.error(error.toString());
  }
}

PaymentError

Thrown for payment-specific issues like insufficient balance or declined transactions.

// error.code: 'payment_failed' | 'insufficient_balance' | 'payment_declined'
// error.statusCode: 400 | 402

ValidationError

Thrown when request parameters are invalid.

// error.code: 'validation_failed' | 'missing_required_field' | 'invalid_parameter'
// error.statusCode: 400

NetworkError

Thrown for connection failures, timeouts, and server errors.

// error.code: 'network_error' | 'timeout'
// error.statusCode: 0 (client-side) or 500+ (server-side)

RateLimitError

Thrown when you exceed the API rate limits.

// error.code: 'rate_limit_exceeded'
// error.statusCode: 429
// error.suggestion: 'Wait 42 seconds before retrying'

WebhookError

Thrown during webhook signature verification failures.

// error.code: 'webhook_signature_invalid' | 'webhook_timestamp_too_old'
// error.statusCode: 400

Handling Patterns

Catch Specific Errors

import {
  ZendFiError,
  AuthenticationError,
  PaymentError,
  RateLimitError,
  isZendFiError,
} from '@zendfi/sdk';

try {
  const payment = await zendfi.createPayment({ amount: 49.99 });
} catch (error) {
  if (error instanceof AuthenticationError) {
    // Re-authenticate or alert the admin
    console.error('API key issue:', error.suggestion);
  } else if (error instanceof RateLimitError) {
    // Back off and retry
    console.warn('Rate limited:', error.suggestion);
  } else if (error instanceof PaymentError) {
    // Show customer-friendly message
    console.error('Payment failed:', error.message);
  } else if (isZendFiError(error)) {
    // Generic ZendFi error
    console.error(`[${error.code}] ${error.message}`);
  } else {
    // Non-ZendFi error
    throw error;
  }
}

Type Guard

Use isZendFiError() to check if any error is a ZendFi error:

import { isZendFiError } from '@zendfi/sdk';

try {
  await zendfi.createPayment({ amount: 10 });
} catch (error) {
  if (isZendFiError(error)) {
    console.log(error.code);       // 'payment_failed'
    console.log(error.docs_url);   // 'https://docs.zendfi.com/errors/payment_failed'
    console.log(error.toJSON());   // structured JSON
  }
}

Error Display

The toString() method formats errors with suggestions and docs links:

try {
  await zendfi.createPayment({ amount: -1 });
} catch (error) {
  console.error(error.toString());
}
// Output:
// [validation_failed] Amount must be positive
// Suggestion: Provide a positive number for the amount field
// Docs: https://docs.zendfi.com/errors/validation_failed

Error Codes Reference

Code	Type	Description
`invalid_api_key`	Authentication	API key not recognized
`api_key_expired`	Authentication	API key has expired
`api_key_revoked`	Authentication	API key was revoked
`insufficient_balance`	Payment	Wallet balance too low
`payment_declined`	Payment	Payment was rejected
`payment_expired`	Payment	Payment window elapsed
`invalid_amount`	Validation	Amount is invalid
`invalid_currency`	Validation	Currency not supported
`missing_required_field`	Validation	Required field not provided
`invalid_parameter`	Validation	Parameter value invalid
`network_error`	Network	Connection failed
`timeout`	Network	Request timed out
`rate_limit_exceeded`	Rate Limit	Too many requests
`webhook_signature_invalid`	Webhook	HMAC signature mismatch
`webhook_timestamp_too_old`	Webhook	Signature expired (>5 min)

Automatic Retries

The SDK retries automatically for transient errors:

5xx server errors: Retried up to config.retries times
Network failures: Retried with exponential backoff
4xx client errors: Never retried

The backoff formula is

2^n \times 1000

ms, where

n

is the attempt number.

Utility Exports

`createZendFiError()`

Factory function that creates the appropriate error subclass based on HTTP status code:

import { createZendFiError } from '@zendfi/sdk';

const error = createZendFiError(401, { message: 'Invalid key' });
// Returns an AuthenticationError

const error2 = createZendFiError(429, { retry_after: 30 });
// Returns a RateLimitError with suggestion "Wait 30 seconds before retrying"

Mapping:

Status Code	Error Class
401	`AuthenticationError`
429	`RateLimitError`
400, 422	`ValidationError`
402	`PaymentError`
0, 500+	`NetworkError`
Other	`ApiError`

`ERROR_CODES`

Const object mapping all SDK error code strings:

import { ERROR_CODES } from '@zendfi/sdk';

ERROR_CODES.INVALID_API_KEY;       // 'invalid_api_key'
ERROR_CODES.RATE_LIMIT_EXCEEDED;   // 'rate_limit_exceeded'
ERROR_CODES.PAYMENT_DECLINED;      // 'payment_declined'
ERROR_CODES.WEBHOOK_SIGNATURE_INVALID; // 'webhook_signature_invalid'

Types

import type { ZendFiErrorType, ZendFiErrorData } from '@zendfi/sdk';

// ZendFiErrorType:
// 'authentication_error' | 'payment_error' | 'validation_error'
// | 'network_error' | 'rate_limit_error' | 'api_error'
// | 'webhook_error' | 'unknown_error'

// ZendFiErrorData: Constructor input for ZendFiError
interface ZendFiErrorData {
  code: string;
  message: string;
  type: ZendFiErrorType;
  suggestion?: string;
  statusCode?: number;
  response?: unknown;
}

​Error Handling

​Error Hierarchy

​Error Properties

​Error Types

​AuthenticationError

​PaymentError

​ValidationError

​NetworkError

​RateLimitError

​WebhookError

​Handling Patterns

​Catch Specific Errors

​Type Guard

​Error Display

​Error Codes Reference

​Automatic Retries

​Utility Exports

​createZendFiError()

​ERROR_CODES

​Types