code: function handleFatalError(fatalError, batch, context) {
    const functionName = tracking.getInvokedFunctionNameWithAliasOrVersion(context);
  
    context.warn(`Disabling event source mapping for function (${functionName}) in response to: `, fatalError);
  
    const rethrowCause = () => {
      throw fatalError;// re-throw the original error
    };
  
    return disableSourceStreamEventSourceMapping(batch, context).then(rethrowCause, rethrowCause);
  }
docs: Handles the given fatal error by attempting to disable the event source mapping between this Lambda & its source
  Kinesis/DynamoDB stream.
  @param {FatalError} fatalError - the fatal error that occurred
  @param {Batch} batch - the batch being processed
  @param {StreamConsumerContext|LambdaAware} context - the context to use
  @return {Promise.<FatalError>} a promise that will always fail with the given fatal error