Make PHP LSP bridge robust: filter noise + buffer JSON output

[jan-dh]

PHP processes often emit deprecation warnings, notices, or other text before/after JSON LSP messages (especially on PHP 8.4+) — breaking the language server’s JSON protocol causing VSCode to crash (see #69
).

• Updated exec() in packages/language-server/src/utils/exec.ts to strip all leading non-JSON noise from stdout before resolving.
• Stdout is now scanned for the first { or [ character, discarding anything before it.
• stderr is still captured but no longer treated as fatal — logged separately by the caller if needed.
• API of exec() and isProcessError() unchanged — fully backwards compatible.

⚠️ Haven't been able to test this locally, so take it for a spin first please 🙏

[moetelo]

I don't really want to rely in trying to find [ or { in the stdout. Deprecation notices possibly could use these characters to format their messages, like [Deprecated]. I see that it's not the case but this solution does not seem that robust to me.

---

In continuation of this comment: #69 (comment)

I was expecting all the warnings go to stderr, and the rest to stdout. Now I see that running php bin/console depends on the user environment (php.ini).

According to the PHP runtime documentation, we can use the ini option display_errors to make the php executable do the expected thing.
https://www.php.net/manual/en/errorfunc.configuration.php#ini.display-errors

Value "stderr" sends the errors to stderr instead of stdout.

And we can pass ini option as an argument to php using -d param:
php -d display_errors=stderr bin/console debug:twig --format json
(src: https://www.php.net/manual/en/features.commandline.options.php)

Now, if we change this:

twiggy/packages/language-server/src/phpInterop/PhpExecutor.ts

Lines 21 to 26 in c65e81f

	const result = await exec(this._phpExecutable, [
	command,
	...args,
	], {
	cwd: this._workspaceDirectory
	});

to this:

const result = await exec(this._phpExecutable, [
    '-d',
    'display_errors=stderr',
    command,
    ...args,
], {
    cwd: this._workspaceDirectory
});

that would hopefully to fix the issue.