wpress_extractor crashes on OS-X Mojave

[dttocs]

When I try to run the current downloadable version, I get the following crash after extracting a subset of files:

./wpress_extractor www.example.com-20180115-163718-420.wpress
Wpress Extracter.
www.example.com-20180115-163718-420.wpress
fatal error: unexpected signal during runtime execution
[signal 0xb code=0x1 addr=0x722b898ad6ce pc=0x1dfde]

runtime stack:
runtime.throw(0x13e800, 0x2a)
	/usr/local/go/src/runtime/panic.go:527 +0x90
runtime.sigpanic()
	/usr/local/go/src/runtime/sigpanic_unix.go:12 +0x5a
runtime.(*gcWork).tryGet(0xc82001f220, 0x3befa8)
	/usr/local/go/src/runtime/mgcwork.go:114 +0x5e
runtime.gcDrainN(0xc82001f220, 0x9b)
	/usr/local/go/src/runtime/mgcmark.go:834 +0x6b
runtime.gcAssistAlloc.func1()
	/usr/local/go/src/runtime/mgcmark.go:237 +0x172
runtime.systemstack(0xc820020a00)
	/usr/local/go/src/runtime/asm_amd64.s:262 +0x79
runtime.mstart()
	/usr/local/go/src/runtime/proc1.go:668

goroutine 1 [running]:
runtime.systemstack_switch()
	/usr/local/go/src/runtime/asm_amd64.s:216 fp=0xc820045a90 sp=0xc820045a88
runtime.gcAssistAlloc(0x200, 0x201)
	/usr/local/go/src/runtime/mgcmark.go:277 +0x21d fp=0xc820045af8 sp=0xc820045a90
runtime.mallocgc(0x200, 0xd0840, 0x1, 0xc820045bf0)
	/usr/local/go/src/runtime/malloc.go:714 +0x535 fp=0xc820045bc8 sp=0xc820045af8
runtime.newarray(0xd0840, 0x200, 0x200)
	/usr/local/go/src/runtime/malloc.go:780 +0xc9 fp=0xc820045c08 sp=0xc820045bc8
runtime.makeslice(0xca320, 0x200, 0x200, 0x0, 0x0, 0x0)
	/usr/local/go/src/runtime/slice.go:32 +0x165 fp=0xc820045c58 sp=0xc820045c08
github.com/yani-/wpress.Reader.Extract(0x7ffeefbff763, 0x33, 0xc820032028, 0xdf, 0x0, 0x0, 0x0)
	/Users/abdullahirfan/go/src/github.com/yani-/wpress/reader.go:127 +0x7e1 fp=0xc820045e60 sp=0xc820045c58
main.main()
	/Users/abdullahirfan/godev/wpress_extractor.go:16 +0x193 fp=0xc820045f50 sp=0xc820045e60
runtime.main()
	/usr/local/go/src/runtime/proc.go:111 +0x2b0 fp=0xc820045fa0 sp=0xc820045f50
runtime.goexit()
	/usr/local/go/src/runtime/asm_amd64.s:1721 +0x1 fp=0xc820045fa8 sp=0xc820045fa0

This is on 10.14.2 (18C54).

I rebuilt using go version go1.11.4 darwin/amd64 and git HEAD from this repo and github.com/yani-/wpress and it worked fine, so I don't think any code change is necessarily needed

I tried to attach my working version to this issue, but github doesn't seem to be liking attachments right now (at least from me).