release(gitforwindows.org): better failure reports of git invocations

When trying to update the site to reflect that Git for Windows v2.49.0
was released, the workflow failed with:

  [...]
  Pushing updates to git-for-windows/git-for-windows.github.io
  Cloning into 'git-for-windows.github.io'...
  Reset branch 'main'
  Auto-detected version 2.49.0 (Mon, 17 Mar 2025 09:40:38 UTC)
  Error: git commit -a -s -m New Git for Windows version failed with status 1
      at callProg (/home/runner/work/git-for-windows-automation/git-for-windows-automation/repository-updates.js:8:33)
      at callGit (/home/runner/work/git-for-windows-automation/git-for-windows-automation/repository-updates.js:13:10)
      at pushRepositoryUpdate (/home/runner/work/git-for-windows-automation/git-for-windows-automation/repository-updates.js:124:5)
      at eval (eval at callAsyncFunction (/home/runner/work/_actions/actions/github-script/v7/dist/index.js:35424:16), <anonymous>:4:7)
      at callAsyncFunction (/home/runner/work/_actions/actions/github-script/v7/dist/index.js:35425:12)
      at main (/home/runner/work/_actions/actions/github-script/v7/dist/index.js:35522:26)
      at /home/runner/work/_actions/actions/github-script/v7/dist/index.js:35497:1
      at /home/runner/work/_actions/actions/github-script/v7/dist/index.js:35553:3
      at Object.<anonymous> (/home/runner/work/_actions/actions/github-script/v7/dist/index.js:35556:12)
      at Module._compile (node:internal/modules/cjs/loader:1469:14)
  Error: Unhandled error: Error: git commit -a -s -m New Git for Windows version failed with status 1
  [...]

This is not helpful. The (hidden) `stdout` wanted to say this:

  On branch main
  Your branch is up to date with 'origin/main'.

  nothing to commit, working tree clean

Let's unhide that kind of errors.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

repository-updates.js

@@ -1,11 +1,19 @@
+const maybeQuote = (arg) =>
+  !arg.match(/[ "']/) ? arg : `'${arg.replace(/'/g, "'\\''")}'`
+const prettyPrintCommand = (prog, parameters) =>
+  `${maybeQuote(prog)} ${parameters.map(maybeQuote).join(' ')}`
 const callProg = (prog, parameters, cwd) => {
   const { spawnSync } = require('child_process')
   const child = spawnSync(prog, parameters, {
     stdio: ['ignore', 'pipe', 'inherit'],
     cwd
   })
-  if (child.error) throw child.error
-  if (child.status !== 0) throw new Error(`${prog} ${parameters.join(' ')} failed with status ${child.status}`)
+  const error = (message) => [
+    `${prettyPrintCommand(prog, parameters)}: ${message}`,
+    `stdout: ${child.stdout}`,
+  ].join('\n')
+  if (child.error) throw new Error(error(`failed with ${child.error}`), { cause: child.error })
+  if (child.status !== 0) throw new Error(error(`failed with status ${child.status}`))
   return child.stdout.toString('utf-8').replace(/\r?\n$/, '')
 }