Updating `depot_tools` requires Xcode but doesn't ensure that Xcode exists

[NoelTautges]

Operating System

macOS 13.5.1, arm64

To Reproduce

1. If you already have everything installed, remove ~/.electron_build_tools/third_party/Xcode.
2. Set up your local Electron environment.
3. Install build-tools.
4. In the electron directory, run e init --root=~/electron depot-tools-testing.

Expected Behavior

Everything to work correctly.

Actual Behavior

The following was logged:

Checking for build-tools updates
Running "git pull --rebase --autostash" in /Users/ntautges/.electron_build_tools
build-tools is up-to-date
Creating /Users/ntautges/electron
Cloning "depot_tools" into /Users/ntautges/.electron_build_tools/third_party/depot_tools
Updating /Users/ntautges/.electron_build_tools/third_party/depot_tools
Running "/Users/ntautges/.electron_build_tools/third_party/depot_tools/update_depot_tools"
Updating depot_tools...
xcrun: error: missing DEVELOPER_DIR path: /Users/ntautges/.electron_build_tools/third_party/Xcode/Xcode.app
depot_tools update failed. Couldn't fetch main branch.
Retry later or reclone depot_tools
xcrun: error: missing DEVELOPER_DIR path: /Users/ntautges/.electron_build_tools/third_party/Xcode/Xcode.app
ERROR Error: Command failed: /Users/ntautges/.electron_build_tools/third_party/depot_tools/update_depot_tools
    at checkExecSyncError (node:child_process:885:11)
    at Object.execFileSync (node:child_process:921:15)
    at depotExecFileSync (/Users/ntautges/.electron_build_tools/src/utils/depot-tools.js:131:23)
    at updateDepotTools (/Users/ntautges/.electron_build_tools/src/utils/depot-tools.js:18:5)
    at Object.ensureDepotTools [as ensure] (/Users/ntautges/.electron_build_tools/src/utils/depot-tools.js:30:5)
    at runGClientConfig (/Users/ntautges/.electron_build_tools/src/e-init.js:79:9)
    at ensureRoot (/Users/ntautges/.electron_build_tools/src/e-init.js:109:5)
    at Command.<anonymous> (/Users/ntautges/.electron_build_tools/src/e-init.js:179:7)
    at Command.listener [as _actionHandler] (/Users/ntautges/.electron_build_tools/node_modules/commander/lib/command.js:480:17)

Additional Information

If you create the config by removing ~/electron and running e init --root=~/electron depot-tools-testing and run e sync, it also happens:

Creating /Users/ntautges/electron/src
Running "gclient sync --with_branch_heads --with_tags -vv" in /Users/ntautges/electron/src
Updating depot_tools...
xcrun: error: missing DEVELOPER_DIR path: /Users/ntautges/.electron_build_tools/third_party/Xcode/Xcode.app
depot_tools update failed. Couldn't fetch main branch.
Retry later or reclone depot_tools
xcrun: error: missing DEVELOPER_DIR path: /Users/ntautges/.electron_build_tools/third_party/Xcode/Xcode.app
ERROR Error: spawnSync /bin/sh ENOENT
    at Object.spawnSync (node:internal/child_process:1110:20)
    at spawnSync (node:child_process:871:24)
    at Object.execSync (node:child_process:952:15)
    at setRemotes (/Users/ntautges/.electron_build_tools/src/e-sync.js:29:8)
    at runGClientSync (/Users/ntautges/.electron_build_tools/src/e-sync.js:62:5)
    at Command.<anonymous> (/Users/ntautges/.electron_build_tools/src/e-sync.js:77:7)
    at Command.listener [as _actionHandler] (/Users/ntautges/.electron_build_tools/node_modules/commander/lib/command.js:480:17)
    at /Users/ntautges/.electron_build_tools/node_modules/commander/lib/command.js:1234:65
    at Command._chainOrCall (/Users/ntautges/.electron_build_tools/node_modules/commander/lib/command.js:1151:12)
    at Command._parseCommand (/Users/ntautges/.electron_build_tools/node_modules/commander/lib/command.js:1234:27)

The built-in version of git on macOS is a shim around the Xcode Command Line Tools install, so when DEVELOPER_DIR is set when e load-xcode hasn't been run yet, it looks to an installation of Xcode that hasn't yet been installed and causes the error.

e build ensures that Xcode is installed before running. Would doing that some thing for e init and e sync (and whatever other commands need it) be a proper fix for this? Regardless, I'd be willing to take a crack at it.

Thank you for taking a look at this.

[codebytere]

@NoelTautges i think that's reasonable! Feel free to request me on the PR.