Error Handling

Overview

Use domain errors from @sws/common/domain instead of plain new Error() for domain-level failures. Each error carries an HTTP status code as a static property, which infrastructure layers can use when mapping to HTTP responses.

Base Error Types

From @sws/common/domain:

Error	Status	When to Use
BadRequestError	400	Invalid input, malformed request
UnauthorizedError	401	Missing or invalid authentication
ForbiddenError	403	Insufficient permissions
NotFoundError	404	Resource not found
RateLimitError	429	Too many requests

Usage Examples

import { NotFoundError, BadRequestError, ForbiddenError } from '@sws/common/domain'

// Resource not found
throw new NotFoundError(`CexAccount with id '${id}' not found`)

// Validation error
throw new BadRequestError(`Invalid CEX name: '${cex}'. Must be one of: binance, kucoin, htx`)

// Authorization
throw new UnauthorizedError('Invalid API credentials')

// Permissions
throw new ForbiddenError('Partner does not have access to this resource')

Custom Domain Errors

Bounded contexts can define their own errors by extending base errors:

// packages/cex-wallets/domain/errors/CexAccountErrors.ts
import { NotFoundError, BadRequestError } from '@sws/common/domain'

export class CexAccountNotFoundError extends NotFoundError {
  constructor(id: string) {
    super(`CexAccount with id '${id}' not found`)
    this.name = 'CexAccountNotFoundError'
  }
}

export class InvalidCexError extends BadRequestError {
  constructor(cex: string) {
    super(`Invalid CEX: '${cex}'. Must be one of: binance, kucoin, htx`)
    this.name = 'InvalidCexError'
  }
}

Error Handling in Services

Catch errors at the application boundary (controllers/event subscribers), not inside domain/application services:

// In event subscriber — log error, don't let it crash the subscriber
async on(event: SomeDomainEvent): Promise<void> {
  try {
    await this.service.run({ ... })
  } catch (error) {
    this.logger.error(`Error in DoSomethingOnEventHappened`, {
      error: error instanceof Error ? error.message : String(error)
    })
  }
}

Error Mapping in Elysia Controllers

Map domain errors to HTTP responses in the Elysia route handler:

import { NotFoundError } from '@sws/common/domain'

app.get('/accounts/:id', async ({ params: { id }, set }) => {
  try {
    return await CexAccountFactory.cexAccountFinderController().run(id)
  } catch (error) {
    if (error instanceof NotFoundError) {
      set.status = NotFoundError.statusCode
      return { error: error.message }
    }
    set.status = 500
    return { error: 'Internal server error' }
  }
})