throwError

type throwError = <T = any>(error: T) => Observable<never>

throwError(X): X

Creates an Observable that throws provided error immediately after subscription.

import { interval, of } from 'light-observable/observable'
import { map, mergeMap, throwError } from 'light-observable/operators'

const stream = interval(1000).pipe(
  map(() => Math.random() > 0.5 ? 42 : 13),
  mergeMap(x => {
    if (x !== 42) {
      return throwError('42 should be the answer')
    } else {
      return of(42)
    }
  })
)