panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x777ab3]

goroutine 52 [running]:
github.com/google/syzkaller/prog.(*serializer).call(0xc0005e1ad0, 0xc00061eff0)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:75 +0x193
github.com/google/syzkaller/prog.(*Prog).serialize(0xc000612540, 0x0)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:46 +0xd8
github.com/google/syzkaller/prog.(*Prog).Serialize(...)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/encoding.go:30
main.(*Proc).logProgram(0xc0000fc700, 0x40975e?, 0xc000078fb8?)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:134 +0x3e
main.(*Proc).executeRaw(0xc0000fc700, 0xc000665ef0, 0xc000612540)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:104 +0x12b
main.(*Proc).loop(0xc0000fc700)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:68 +0x148
created by main.main in goroutine 1
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:269 +0x1195
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