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Error handling

All SDK errors extend FourMicaError. Import the specific classes to branch on failure type.
ErrorWhen it is thrown
ConfigErrorInvalid ConfigBuilder input.
RpcErrorThe 4Mica core service returned an error. Carries .status and .body.
SigningErrorThe signing scheme is unsupported, or the signer address does not match the claims.
ContractErrorAn on-chain call failed or returned an unexpected result.
VerificationErrorA BLS certificate failed to decode or its domain did not match.
X402ErrorAn x402 flow error: bad scheme, tab resolution, or settlement.
AuthErrorBase class for all authentication errors.
AuthMissingConfigErrorlogin() was called but auth is not configured.
The Auth* family also includes AuthUrlError, AuthTransportError, AuthDecodeError, AuthApiError, and AuthConfigError, all extending AuthError.

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Distinguishing errors

Import the classes you want to handle and branch with instanceof. 
import {
  ConfigError, // invalid ConfigBuilder input
  RpcError, // 4Mica core service error (has .status and .body)
  SigningError, // signing scheme unsupported or address mismatch
  ContractError, // on-chain call failed or unexpected result
  VerificationError, // BLS certificate decode or domain mismatch
  X402Error, // x402 flow error
  AuthError, // base class for all auth errors
  AuthMissingConfigError, // auth not configured when login() is called
} from "@4mica/sdk";

try {
  const verified = await client.recipient.verifyPaymentGuarantee(cert);
  await client.recipient.claimNetCredit(cycleId);
} catch (err) {
  if (err instanceof VerificationError) {
    // bad certificate — decode failed or domain mismatch
  } else if (err instanceof ContractError) {
    // on-chain settlement failed
  } else if (err instanceof RpcError) {
    console.error(err.status, err.body);
  }
}
Every error extends FourMicaError, so you can catch that base class to handle any SDK failure in one place.

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Next steps

Overview

Install the SDK and see the capabilities at a glance.

Client operations

Deposit collateral, sign payments, and settle cleared cycles.