Go の「すべてのゴルーチンがスリープ状態」デッドロックを解決する方法?

go func() {
    wg.Wait()
    close(ch)
}()

package main

import (
    "fmt"
    "sync"
    "time"
)

type Item struct {
    name string
}

type Truck struct {
    Cargo []Item
    name  string
}

func UnloadTrucks(c chan Truck) {

    for t := range c {
        fmt.Printf("%s has %d items in cargo: %s\n", t.name, len(t.Cargo), t.Cargo[0].name)
    }

}

func main() {
    trucks := make([]Truck, 2)

    ch := make(chan Truck)

    var wg sync.WaitGroup

    for i, _ := range trucks {

        trucks[i].name = fmt.Sprintf("Truck %d", i+1)

        fmt.Printf("Building %s\n", trucks[i].name)
    }

    for t := range trucks {
        wg.Add(1)
        go func(tr Truck) {

            itm := Item{}
            itm.name = "Groceries"

            fmt.Printf("Loading %s\n", tr.name)
            tr.Cargo = append(tr.Cargo, itm)
            ch <- tr
            wg.Done()

        }(trucks[t])
    }

    time.Sleep(50 * time.Millisecond)
    fmt.Println("Unloading Trucks")
    UnloadTrucks(ch)

    fmt.Println("Done")
}