ternary failed

pass.go

package main

import (
	"fmt"
)

func main() {
	var foo = map[bool]string{true: "foo", false: "bar"}[true]
	fmt.Println("Hello Go", foo)

	var bar = map[bool]string{true: "foo", false: "bar"}[false]
	fmt.Println("Hello Go", bar)
}

/*
Hello Go foo
Hello Go bar

Program exited.
*/

sample.go

package main

import (
	"fmt"
	"os"
)

func sendCapture() string {
	fmt.Println("Send Capture")
	return "url"
}

func sendFile(filename string) string {
	fmt.Println("Send File", filename)
	return "url"
}

func main() {
	var url = map[bool]string{true: sendCapture(), false: sendFile(os.Args[1])}[len(os.Args) == 1]
	fmt.Println("Hello Go", url)
}

/*
1
Send Capture
panic: runtime error: index out of range

goroutine 16 [running]:
runtime.panic(0x113be0, 0x1a39dc)
	/tmp/sandbox/go/src/pkg/runtime/panic.c:279 +0x120
main.main()
	/tmpfs/gosandbox-992bfd34_3434ac75_ca326031_a55b9406_b94753c2/prog.go:20 +0x3a0

goroutine 19 [runnable]:
runfinq()
	/tmp/sandbox/go/src/pkg/runtime/mgc0.c:2606
runtime.goexit()
	/tmp/sandbox/go/src/pkg/runtime/proc.c:1445
 [process exited with non-zero status]

Program exited.
*/