Missing error check in fielpath.WalkFunc

[geropl]

Stacktrace:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x5584e9]

goroutine 1 [running]:
github.com/32leaves/bel.NewParsedSourceEnumHandler.func1(0x615603, 0x15, 0x0, 0x0, 0x653880, 0xc000100b10, 0x40, 0x5f6a00)
	/workspace/go/pkg/mod/github.com/32leaves/bel@v1.0.1/enum.go:32 +0x49
path/filepath.Walk(0x615603, 0x15, 0xc0001318e0, 0x0, 0x1000000006595a0)
	/home/gitpod/go/src/path/filepath/path.go:404 +0x6a
github.com/32leaves/bel.NewParsedSourceEnumHandler(0x615603, 0x15, 0x0, 0x0, 0x653880)
	/workspace/go/pkg/mod/github.com/32leaves/bel@v1.0.1/enum.go:31 +0xf7
main.main()
	/tmp/build/gitpod-core-components-licensor-typescript--lib.b4eb6140f12b76cf914379726822bcd956b92256/ee/genapi.go:25 +0x8f
exit status 2