Panic when using void return value of a function in a for loop expression

[vidya88]

@asahi3g commented on Mar 12

To Reproduce

package main
func foo()() {
}

func main() {
	for foo() {
		printf("true\n")
	}
}

Expected behavior Compilation error

Screenshots

panic: runtime error: index out of range

goroutine 1 [running, locked to thread]:
github.com/skycoin/cx/cxgo/actions.IterationExpressions(0x0, 0x0, 0x0, 0xc0000100e0, 0x1, 0x1, 0x0, 0x0, 0x0, 0xc000010140, ...)
	/home/reash/go/src/github.com/skycoin/cx/cxgo/actions/expressions.go:43 +0x11ba
main.yyParse(0xa849c0, 0xc00008e050, 0x0)
	/home/reash/go/src/github.com/skycoin/cx/cxgo/cxgo.go:2391 +0xa17b
main.main()
	/home/reash/go/src/github.com/skycoin/cx/cxgo/cxgo.nn.go:8848 +0x917

Desktop:

• OS: Linux
• CX Version : 0.6.1, d8775bf