Harden spawn, signal handling, and null-error guards across run command and runtime hooks

[Copilot]

Several robustness gaps existed in the run command and the injector/auto/matcher modules: hard-coded "node" binary, missing signal-kill detection, no exit on spawn error, and unguarded property access on non-Error throws.

Changes

bin/index.js

• Replace spawn("node", ...) with spawn(process.execPath, ...) so the CLI always uses the same Node binary that invoked it
• Add explicit { stdio: ["inherit", "pipe", "pipe"] } — stdin is inherited, stdout/stderr are piped
• close handler now accepts (code, signal); code === null is treated as a signal kill, logs the signal, and exits 1; otherwise uses process.exit(code ?? 1) as a safety net
• child.on("error") now calls process.exit(1) after logging, preventing the CLI from hanging on spawn failures

lib/auto.js

• Guard against non-Error throws: const msg = (err && err.message) ? err.message : String(err) passed to findError instead of bare err.message

lib/injector.js

• Both uncaughtException and unhandledRejection handlers normalize the thrown value before accessing .stack/.message:

  const errStr = err !== null && typeof err === "object"
    ? (err.stack || err.message)
    : String(err ?? "unknown error");

  Prevents a secondary crash when null, a primitive, or a non-Error is thrown.

lib/matcher.js

• Add if (typeof input !== "string") input = String(input) before input.toLowerCase() to handle non-string values passed to findError

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