PHP: Handle request errors in PHPRequestHandler, return response code 500

[kozer]

What is this PR doing?

Moves the handling of PHP fatal errors from a service worker message listener, where only the in-browser Playground can use it, to PHPRequestHandler, that allows all the Playground apps like Studio and wp-now to benefit.

In addition, this PR ensures that HTTP 500 Internal Server Error is returned if PHP exits with a non-zero code. This is required because PHP itself seems to happily return HTTP 200 in those cases.

What problem is it solving?

Studio app is showing error logs and is hung under certain scenarios. This pr fixes that.

How is the problem addressed?

By catching the error, and returning the error response.

Testing Instructions

The easiest way I found to test it was via Studio, where the problem appeared originally.

• Clone the Studio app
• Change package.json and replace @php-wasm references with the following:

		"@php-wasm/util": "file:../wordpress-playground/dist/packages/php-wasm/util",
		"@php-wasm/node-polyfills": "file:../wordpress-playground/dist/packages/php-wasm/node-polyfills",
		"@php-wasm/universal": "file:../wordpress-playground/dist/packages/php-wasm/universal",

• Change webpack.main.config.ts and replace the externals object with the following:

externals: {
		'@php-wasm/node': '@php-wasm/node',
		'@php-wasm/universal': '@php-wasm/universal',
		'@php-wasm/util': '@php-wasm/util',
		'@php-wasm/node-polyfills': '@php-wasm/node-polyfills',
	},

• Clone this pr.
• Run npm i
• Run npx nx reset && npm run build
• Back to the Studio repo, run npm i
• Create a new site.
• Install WooCommerce
• Reload the wp-admin
• Ensure that the dashboard is showing as expected instead of hanging.

Run tests manually

1 From the root of the project run: npx --expose-gc nx run php-wasm-node:test --testFile ./packages/php-wasm/node/src/test/php-request-handler.spec.ts --skipNxCache

[kozer]

NOTE:
The above use case solves the issue, however, I am not sure if this is the way to go. Let me explain why.
Although woo, produces a response with httpsStatusCode that is 500, and exitCode 255, it's not reflected in the network tab. The network tab shows the status 200 in all its responses.
Note that if we produce another critical error ( eg die in wp-config.php ), we immediately display an error screen, and I get status 500.
Another thing to note is that while I was testing this, I saw some PHPResponse objects that had httpStatusCode of 200, but exitCode of 255, which seems strange.

[adamziel]

This will work as expected once #1252 lands and base-php.ts is updated as follows (PHP doesn’t seem to set the status code to 500 on failure):

		return new PHPResponse(
			exitCode === 0 ? httpStatusCode : 500,

[kozer]

Exported a new interface and added the change @adamziel suggested.
Waiting for #1251

[kozer]

Updated the PR , and added some tests