Handling Errors

In real apps, things go wrong. A network request might fail, a data transformation might error out, or an external service might be unavailable. When this happens, App-Compose isolates the failure so the rest of your app continues to work as expected.

Task errors only come from run.fn or enabled.fn.

Failure behavior

If a Task fails, App-Compose marks it as failed and keeps the app running. Any Task that strictly depends on it, directly or through Tags, is marked as skipped.

import { status } from "@grlt-hub/app-compose"

const alpha = createTask({
  name: "alpha",
  run: {
    fn: () => {
      throw new Error("Oops!")
    },
  },
})

const beta = createTask({
  name: "alpha",
  run: {
    fn: () => {},
    context: { alpha },
  },
})

const gamma = createTask({
  name: "gamma",
  run: {
    fn: (ctx) => {
      ctx.forEach((x) => console.log(x))
    },
    context: [
      {
        "alpha.status.name": status(alpha).name,
      },
      { "beta.status.name": status(beta).name },
    ],
  },
})

compose({}).stage([alpha]).stage([beta]).stage([gamma]).run()

Logging Failures

By default, App-Compose logs a warning to the console when a Task fails. You can customize this behavior with the onTaskFail. This is useful for separating dev and production handling, for example sending errors to a logging system like Sentry.

const alpha = createTask({
  name: "alpha",
  run: {
    fn: () => {
      throw new Error("Oops!")
    },
  },
})

const onTaskFail = (task) => {
  console.log(`*** ERROR *** \n ${String(task.id)} :: ${task.error}`)
}

compose({
  // 👇 Handle task failures here
  log: { onTaskFail },
})
  .stage([alpha])
  .run()