A fix that uses a third channel

bug_fix1.go

package main

import (
	"fmt"
	"math/rand"
	"sync"
	"time"
)

func getStrings(fileName string) (string, error) {
	time.Sleep(400 * time.Millisecond)
	r := rand.Intn(100)
	if r%2 != 0 {
		return "", fmt.Errorf("FAKE ERROR: %s", fileName)
	}
	return fileName, nil
}

func main() {
	rand.Seed(time.Now().UnixNano())
	var wg sync.WaitGroup

	workers := 4
	wg.Add(workers)

	jobCh := make(chan string)
	errCh := make(chan error)
	wgCh := make(chan struct{})

	go func() {
		for i := 0; i < workers; i++ {
			go func() {
				defer wg.Done()
				for fileName := range jobCh {
					in, err := getStrings(fileName)
					if err != nil {
						errCh <- err
						fmt.Println(err)
						break
					}
					fmt.Println("string processed: ", in)
				}
			}()
		}
		wg.Wait()
		close(wgCh)
	}()

	testStrings := []string{"one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "", "", "", "", "", ""}
	b := false
	for _, s := range testStrings {
		if b {
			break
		}
		select {
		case ch := <-errCh:
			fmt.Println("error found: ", ch)
			b = true
		case jobCh <- s:
			fmt.Println("adding job: ", s)
		case <-wgCh:
			fmt.Println("done")
			return
		}

	}
	close(jobCh)
	select {
	case ec := <-errCh:
		fmt.Println("f: ", ec)
	case <-wgCh:
		fmt.Println("wg done")
		break
	}
}