Failed to cross compile linux -> darwin

[jonatino]

I'm trying to cross compile on ubuntu 18 to darwin but it fails with the following errors:

Run go build -o s3/darwin
  go build -o s3/darwin
  shell: /bin/bash -e {0}
  env:
    GOROOT: /opt/hostedtoolcache/go/1.14.2/x64
    GOOS: darwin
    GOARCH: amd64
    LD_LIBRARY_PATH: ./libs/darwin/
# github.com/ImVexed/muon
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:11:2: imported and not used: "github.com/ImVexed/muon/ultralight"
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:16:12: undefined: ULWindow
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:17:12: undefined: ULOverlay
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:18:12: undefined: ULView
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:19:12: undefined: ULApp
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:162:34: undefined: JSContextRef
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:162:56: undefined: JSObjectRef
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:162:125: undefined: JSValueRef
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:203:22: undefined: JSContextRef
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:203:42: undefined: JSValueRef
##[error]../../../go/pkg/mod/github.com/!im!vexed/muon@v0.0.0-20191209030120-589db8f0f250/muon.go:203:42: too many errors
##[error]Process completed with exit code 2.

Is there anything else I need to pass in to make this work?