panic: assignment to entry in nil map

goroutine 1 [running]:
github.com/google/syzkaller/pkg/signal.Serial.Deserialize(0xc00008a000, 0x0, 0x0, 0xc000244000, 0x4a7, 0x0, 0x0)
	/syzkaller/gopath/src/github.com/google/syzkaller/pkg/signal/signal.go:91 +0xa0
main.(*Fuzzer).addInputFromAnotherFuzzer(0xc0000a9a00, 0xc000096c00, 0x2a, 0xc0004423c0, 0x122, 0x122, 0xc00008a000, 0x4a7, 0x4a7, 0xc000244000, ...)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:439 +0x103
main.(*Fuzzer).poll(0xc0000a9a00, 0x99e200, 0x0, 0xc0003c1e78)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:412 +0x427
main.main()
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:267 +0x11d6
login: