为什么在 Golang 中发送超过缓冲通道大小的值会导致死锁错误？

// By default channels are _unbuffered_, meaning that they

// will only accept sends (`chan <-`) if there is a

// corresponding receive (`<- chan`) ready to receive the

// sent value. _Buffered channels_ accept a limited

// number of values without a corresponding receiver for

// those values.

package main

import "fmt"

func main() {

// Here we `make` a channel of strings buffering up to

// 2 values.

messages := make(chan string, 2)

// Because this channel is buffered, we can send these

// values into the channel without a corresponding

// concurrent receive.

messages <- "buffered"

messages <- "channel"

messages <- "channel1" //I added this.

// Later we can receive these two values as usual.

fmt.Println(<-messages)

}

它抛出的错误：

fatal error: all goroutines are asleep - deadlock!

goroutine 1 [chan send]:

main.main()

/tmp/sandbox795158698/prog.go:23 +0x8d

问题：