chore: fold in fixes from open PRs (#127, #148, #112)

Addresses long-standing open PRs whose intent fits the cross-spawn /
hook-hardening cleanup:

* #127 - install.js: "backuped" -> "backed up".
* #148 - magit workaround: emit `unset GIT_LITERAL_PATHSPECS` in the
  generated `.git/hooks/pre-commit` wrapper, and also at the top of
  the package's `hook` script for defense-in-depth, so hooks invoked
  from emacs/magit behave the same as on the command line.
* #112 - resilience for missing pre-commit package: when a user
  switches to a branch without `node_modules`, the generated wrapper
  now exits 0 instead of failing the commit, and the `hook` script
  detects an unresolvable `pre-commit` package and skips with a
  friendly warning instead of throwing a Node module-not-found stack.

Made-with: Cursor

Author: 3rd-Eden

hook

@@ -1,5 +1,12 @@
 #!/usr/bin/env bash
 
+#
+# Defense-in-depth for magit (the .git/hooks wrapper unsets it too); ensures
+# hooks invoked from emacs/magit behave the same as on the CLI.
+# https://magit.vc/manual/magit/My-Git-hooks-work-on-the-command_002dline-but-not-inside-Magit.html
+#
+unset GIT_LITERAL_PATHSPECS
+
 HAS_NODE=`which node 2> /dev/null || which nodejs 2> /dev/null || which iojs 2> /dev/null`
 
 #
@@ -46,14 +53,32 @@ if [[ -n "$REPO_ROOT" ]]; then
   cd "$REPO_ROOT" || exit 1
 fi
 
+#
+# Resolve the entry point of the `pre-commit` package via Node so we work for
+# Yarn Plug'n'Play, hoisted, and nested layouts. If the package cannot be
+# resolved (e.g. the user switched to a branch with no `node_modules`, or
+# uninstalled `pre-commit`) skip the hook with exit 0 instead of failing the
+# commit -- a missing dev dependency must not block work.
+#
+RESOLVED=
+RESOLVE_RC=1
+if [[ -n "$BINARY" ]]; then
+  RESOLVED="$("$BINARY" -e "try { console.log(require.resolve('pre-commit')); } catch (e) { process.exit(2); }" 2>/dev/null)"
+  RESOLVE_RC=$?
+fi
+
 #
 # Add --dry-run cli flag support so we can execute this hook without side effects
 # and see if it works in the current environment
 #
 if [[ $* == *--dry-run* ]]; then
-  if [[ -z "$BINARY" ]]; then
+  if [[ -z "$BINARY" ]] || [[ "$RESOLVE_RC" -ne 0 ]] || [[ -z "$RESOLVED" ]]; then
     exit 1
   fi
 else
-  exec "$BINARY" "$("$BINARY" -e "console.log(require.resolve('pre-commit'))")"
+  if [[ "$RESOLVE_RC" -ne 0 ]] || [[ -z "$RESOLVED" ]]; then
+    echo "pre-commit: 'pre-commit' package is not installed; skipping hooks (run \`npm install\` to re-enable)." >&2
+    exit 0
+  fi
+  exec "$BINARY" "$RESOLVED"
 fi

install.js

@@ -89,7 +89,7 @@ if (exists(precommit) && !fs.lstatSync(precommit).isSymbolicLink()) {
   console.log('pre-commit:');
   console.log('pre-commit: Detected an existing git pre-commit hook');
   fs.writeFileSync(precommit +'.old', fs.readFileSync(precommit));
-  console.log('pre-commit: Old pre-commit hook backuped to pre-commit.old');
+  console.log('pre-commit: Old pre-commit hook backed up to pre-commit.old');
   console.log('pre-commit:');
 }
 
@@ -109,8 +109,25 @@ if (os.platform() === 'win32') {
   hookLauncher = hookLauncher.replace(/\\/g, '/');
 }
 
-var precommitContent = '#!/usr/bin/env bash' + os.EOL
-  + 'exec bash ' + shellSingleQuote(hookLauncher) + ' "$@"' + os.EOL;
+//
+// Generated wrapper:
+//   * Unsets GIT_LITERAL_PATHSPECS so hooks invoked from magit/emacs behave the
+//     same as on the command line. See:
+//     https://magit.vc/manual/magit/My-Git-hooks-work-on-the-command_002dline-but-not-inside-Magit.html
+//   * If the package's `hook` script is missing (e.g. user switched to a branch
+//     without `node_modules`, or removed the `pre-commit` package), skip
+//     silently with exit 0 so commits are not blocked.
+//
+var precommitContent = [
+  '#!/usr/bin/env bash',
+  'unset GIT_LITERAL_PATHSPECS',
+  'HOOK=' + shellSingleQuote(hookLauncher),
+  'if [ ! -f "$HOOK" ]; then',
+  '  exit 0',
+  'fi',
+  'exec bash "$HOOK" "$@"',
+  ''
+].join(os.EOL);
 
 //
 // It could be that we do not have rights to this folder which could cause the