Trying to build android, getting weird clang error

Ryans-MBP:android ryan$ sh build_and_publish.sh 
Repo '/Users/ryan/src/github.com/keybase/client' looks good. Pulling...
Already up-to-date.
yarn install v0.19.1
[1/4] 🔍  Resolving packages...
success Already up-to-date.
$ yarn run _helper postinstall
yarn run v0.19.1
$ yarn run _node -- desktop/yarn-helper.js postinstall
yarn run v0.19.1
$ cross-env BABEL_ENV=yarn babel-node desktop/yarn-helper.js postinstall
null
null
null
✨  Done in 2.21s.
✨  Done in 2.75s.
✨  Done in 4.30s.
yarn global v0.19.1
warning No license field
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
[4/4] 📃  Building fresh packages...
success Installed "react-native-cli@2.0.1" with binaries:
      - react-native
warning No license field
✨  Done in 1.10s.
Building Go library
yarn run v0.19.1
$ ./react-native/gobuild.sh android 
Using temp GOPATH: /tmp/go-android
Clearing /tmp/go-android/src
Getting client (using local GOPATH)... To use git master, set LOCAL_CLIENT=0
Getting KBFS (via git clone)... To use local copy, set LOCAL_KBFS=1
Cloning into 'kbfs'...
remote: Counting objects: 29888, done.
remote: Compressing objects: 100% (234/234), done.
remote: Total 29888 (delta 144), reused 0 (delta 0), pack-reused 29654
Receiving objects: 100% (29888/29888), 38.36 MiB | 7.53 MiB/s, done.
Resolving deltas: 100% (22436/22436), done.
Re-vendoring...
Build gomobile...
Doing gomobile init (to skip, set SKIP_GOMOBILE_INIT=1)
/tmp/go-android/bin/gomobile: xcrun --find: exit status 72
xcodebuild: error: SDK "iphonesimulator" cannot be located.
xcrun: error: unable to find utility "clang", not a developer tool or in PATH

error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
Already on 'master'
Your branch is up-to-date with 'origin/master'.
Ryans-MBP:android ryan$ which clang
/usr/bin/clang
Ryans-MBP:android ryan$ 

Start with android/build_and_publish.sh and react-native/gobuild.sh, then inspect the gomobile init step that reports xcrun, iphonesimulator, and clang errors. Reproduce the Android build on the reported macOS setup; done means the build proceeds past gomobile initialization without the SDK or clang errors.