How to trigger a panic when working with a channel? What happens with nil-channel and closed channel operations?

Panic in Go when working with channels occurs in the following cases:

• Sending a value to a closed channel (chan <- value) causes a panic.
• Closing an already closed channel (close(chan)) causes a panic.

Regarding nil-channels:

• Send and receive operations with a nil-channel block forever (deadlock), but do not cause a panic.

Example:

var ch chan int // nil-channel

// <-ch // blocks forever
// ch <- 1 // blocks forever

ch = make(chan int)
close(ch)

// ch <- 1 // panic: send on closed channel

close(ch) // panic: close of closed channel