panic: bad arg kind: <nil>

goroutine 24 [running]:
github.com/google/syzkaller/prog.clone(0x0, 0x0, 0xc002821e38, 0xc0012a78c0, 0xc00134c980)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/clone.go:79 +0x954
github.com/google/syzkaller/prog.(*Prog).Clone(0xc0004e9f80, 0xc0014ea2a0)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/clone.go:24 +0x279
main.(*Proc).loop(0xc001494940)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:94 +0x3ca
created by main.main
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:259 +0x114c