crash when encountering some CJK text amongst English

[mark-summerfield]

I get a panic when trying to read the attached PDF file.

goroutine 1 [running]:
github.com/ledongthuc/pdf.(*buffer).errorf(...)
	/home/mark/opt/gows/pkg/mod/github.com/ledongthuc/[email protected]/lex.go:82
github.com/ledongthuc/pdf.(*buffer).readHexString(0xc0002a1720)
	/home/mark/opt/gows/pkg/mod/github.com/ledongthuc/[email protected]/lex.go:203 +0x2f6
github.com/ledongthuc/pdf.(*buffer).readToken(0xc0002a1720)
	/home/mark/opt/gows/pkg/mod/github.com/ledongthuc/[email protected]/lex.go:157 +0x165
github.com/ledongthuc/pdf.Interpret({0xc0001301e0?, {0x1138a0?, 0xc0?}, {0x4f8bc0?, 0xc000128120?}}, 0xc0002a18c0)
	/home/mark/opt/gows/pkg/mod/github.com/ledongthuc/[email protected]/ps.go:64 +0x145
github.com/ledongthuc/pdf.Page.Content({{0xc0001301e0?, {0x1?, 0x0?}, {0x4f1ec0?, 0xc000120a80?}}})
	/home/mark/opt/gows/pkg/mod/github.com/ledongthuc/[email protected]/page.go:816 +0x2b5
main.getChars(0x53cb78?, 0x1, 0x5126f3?)
	/home/mark/app/go/pdfdump/text.go:14 +0x85
main.outputWords(0xc0002a1f00, 0x40c41e?, 0x400000?, 0xc0000666b0?)
	/home/mark/app/go/pdfdump/output.go:75 +0x1ca
main.output(0xc000113f00)
	/home/mark/app/go/pdfdump/output.go:33 +0x1a5
main.main()
	/home/mark/app/go/pdfdump/pdfdump.go:12 +0x99

99.pdf