Error Handling

Typed error classes, status codes, request IDs, and best practices for handling API errors.

Error Classes

The SDK provides typed error classes for every failure scenario. Every error instance includes a request ID for support correlation.

TypeScript

import {
  LendIQ,
  LendIQError,
  AuthenticationError,
  NotFoundError,
  ValidationError,
  RateLimitError,
} from "@lendworks/lendiq";

const client = new LendIQ({ apiKey: "liq_live_..." });

try {
  await client.deals.get(99999);
} catch (err) {
  if (err instanceof NotFoundError) {
    console.log("Deal not found");
    console.log(err.statusCode);  // 404
    console.log(err.requestId);   // "req_abc123"
    console.log(err.body);        // { error: "Deal not found" }
  } else if (err instanceof AuthenticationError) {
    console.log("Invalid credentials:", err.message);
  } else if (err instanceof ValidationError) {
    console.log("Validation failed:", err.body);
  } else if (err instanceof RateLimitError) {
    console.log(`Rate limited. Retry after ${err.retryAfter} seconds`);
  } else if (err instanceof LendIQError) {
    console.log(err.message, err.statusCode);
  }
}

Python

from lendiq import (
    LendIQ,
    LendIQError,
    AuthenticationError,
    NotFoundError,
    ValidationError,
    RateLimitError,
)

client = LendIQ(api_key="liq_live_...")

try:
    client.deals.get(99999)
except NotFoundError as e:
    print("Deal not found")
    print(e.status_code)   # 404
    print(e.request_id)    # "req_abc123"
except AuthenticationError as e:
    print("Invalid credentials:", e.message)
except ValidationError as e:
    print("Validation failed:", e.body)
except RateLimitError as e:
    print(f"Rate limited. Retry after {e.retry_after} seconds")
except LendIQError as e:
    print(e.message, e.status_code)

Error Types

Class	Status	When
`AuthenticationError`	401	Invalid or expired API key
`ValidationError`	422	Request body fails validation
`NotFoundError`	404	Resource does not exist
`RateLimitError`	429	Rate limit exceeded (check retryAfter)
`LendIQError`	Any	Base class for all other API errors

Request ID Tracking

Every API response includes a request ID. You can access the last request ID on the client instance for logging and support correlation.