Drone-docker-runner memory fault

When execute drone-docker-runner exec for https://github.com/drone/drone-cli project.

The following issue occurs:

$ ../bin/drone-runner-docker exec
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x8135bf]

goroutine 1 [running]:
github.com/drone/runner-go/secret.(*combined).Find(0xc00025e450, 0xb62c70, 0xc000022088, 0xc0004e28d0, 0xc0004b7090, 0xc00025e488, 0x8cce15)
	/home/stevenlee/go/pkg/mod/github.com/drone/[email protected]/secret/combine.go:25 +0x5f
github.com/drone-runners/drone-runner-docker/engine/compiler.(*Compiler).findSecret(0xc00025fbb0, 0xb62c70, 0xc000022088, 0xc0003902e8, 0xb62df8, 0xc0003dce00, 0xc0003be5a0, 0xc0003ec500, 0xc0003f4300, 0xc000393500, ...)
	/home/stevenlee/Temp/temp/drone-runner-docker/engine/compiler/compiler.go:593 +0x157
github.com/drone-runners/drone-runner-docker/engine/compiler.(*Compiler).Compile(0xc00025fbb0, 0xb62c70, 0xc000022088, 0xc0003902e8, 0xb62df8, 0xc0003dce00, 0xc0003be5a0, 0xc0003ec500, 0xc0003f4300, 0xc000393500, ...)
	/home/stevenlee/Temp/temp/drone-runner-docker/engine/compiler/compiler.go:393 +0x2865
github.com/drone-runners/drone-runner-docker/command.(*execCommand).run(0xc0003da4e0, 0xc00048a000, 0x0, 0x0)
	/home/stevenlee/Temp/temp/drone-runner-docker/command/exec.go:150 +0xa3c
gopkg.in/alecthomas/kingpin%2ev2.(*actionMixin).applyActions(0xc0003f00d8, 0xc00048a000, 0x0, 0x0)
	/home/stevenlee/go/pkg/mod/gopkg.in/alecthomas/[email protected]/actions.go:28 +0x6d
gopkg.in/alecthomas/kingpin%2ev2.(*Application).applyActions(0xc0003ee690, 0xc00048a000, 0x0, 0x0)
	/home/stevenlee/go/pkg/mod/gopkg.in/alecthomas/[email protected]/app.go:557 +0xdf
gopkg.in/alecthomas/kingpin%2ev2.(*Application).execute(0xc0003ee690, 0xc00048a000, 0xc000395020, 0x1, 0x1, 0x0, 0x0, 0x0, 0xa075a0)
	/home/stevenlee/go/pkg/mod/gopkg.in/alecthomas/[email protected]/app.go:390 +0x95
gopkg.in/alecthomas/kingpin%2ev2.(*Application).Parse(0xc0003ee690, 0xc00001e070, 0x1, 0x1, 0xc0003ee690, 0xc00025ff78, 0x406365, 0xc00002e178)
	/home/stevenlee/go/pkg/mod/gopkg.in/alecthomas/[email protected]/app.go:222 +0x228
github.com/drone-runners/drone-runner-docker/command.Command()
	/home/stevenlee/Temp/temp/drone-runner-docker/command/command.go:32 +0x10f
main.main()
	/home/stevenlee/Temp/temp/drone-runner-docker/main.go:13 +0x25

I see you have the code cloned locally. have you considered sending a patch to https://github.com/drone-runners/drone-runner-docker ?