packages/components/.storybook/run.js doesn't work in CI

While working on #607 I noticed there were errors in .storybook/run.js that were implicitly skipped in Node 14.
I've added an explicit silencing for the build to pass in Node 18, but this still needs to be fixed.
See for example https://app.travis-ci.com/github/applandinc/appmap-js/jobs/573053743#L1231 :

➤ YN0000: [@appland/components]: (node:7001) UnhandledPromiseRejectionWarning: Error: Command failed: git diff origin/main --name-only
➤ YN0000: [@appland/components]: fatal: ambiguous argument 'origin/main': unknown revision or path not in the working tree.
➤ YN0000: [@appland/components]: Use '--' to separate paths from revisions, like this:
➤ YN0000: [@appland/components]: 'git <command> [<revision>...] -- [<file>...]'
➤ YN0000: [@appland/components]: 
➤ YN0000: [@appland/components]:     at ChildProcess.exithandler (child_process.js:383:12)
➤ YN0000: [@appland/components]:     at ChildProcess.emit (events.js:400:28)
➤ YN0000: [@appland/components]:     at maybeClose (internal/child_process.js:1088:16)
➤ YN0000: [@appland/components]:     at Socket.<anonymous> (internal/child_process.js:446:11)
➤ YN0000: [@appland/components]:     at Socket.emit (events.js:400:28)
➤ YN0000: [@appland/components]:     at Pipe.<anonymous> (net.js:686:12)
➤ YN0000: [@appland/components]: (Use `node --trace-warnings ...` to show where the warning was created)
➤ YN0000: [@appland/components]: (node:7001) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
➤ YN0000: [@appland/components]: (node:7001) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
➤ YN0000: [@appland/components]: Process exited (exit code 0), completed in 6s 668ms

Start with packages/components/.storybook/run.js and inspect the git diff origin/main --name-only call shown in the CI log. Reproduce the Storybook build in CI with Node 18; done means the command no longer produces an unhandled promise rejection or causes the build to fail.