Create directory node before mounting

Author: bgrgicak

packages/php-wasm/node/src/lib/node-fs-mount.ts

@@ -2,8 +2,31 @@ import type { MountHandler } from '@php-wasm/universal';
 
 export function createNodeFsMountHandler(localPath: string): MountHandler {
 	return async function (php, FS, vfsMountPoint) {
+		/**
+		 * DON'T MERGE THIS.
+		 * This is a temporary workaround to demonstrate how mounting requires the mount point to be a directory.
+		 *
+		 * Emscripten requires the mount point to be a directory.
+		 * By creating a directory we can even mount a file over it as long as the paths match.
+		 * PHP-WASM source: https://github.com/WordPress/wordpress-playground/blob/trunk/packages/php-wasm/node/asyncify/php_8_0.js#L2679
+		 *
+		 * When Emscripten attempt to mount a local path into VFS, it looks up the path
+		 * and adds the local path as a mount to the VFS Node.
+		 * PHP-WASM source: https://github.com/WordPress/wordpress-playground/blob/trunk/packages/php-wasm/node/asyncify/php_8_0.js#L2700
+		 *
+		 * For mounting to work, the Node must exist in VFS and be a directory.
+		 * If the Node doesn't exist, the mount fails with error 44 (MEMFS.doesNotExistError).
+		 * PHP-WASM source: https://github.com/WordPress/wordpress-playground/blob/trunk/packages/php-wasm/node/asyncify/php_8_0.js#L1201
+		 */
+		try {
+			FS.lookupPath(vfsMountPoint);
+		} catch (e) {
+			// FS.lookupPath will throw an error if the path doesn't exist.
+			FS.mkdirTree(vfsMountPoint);
+		}
 		FS.mount(FS.filesystems['NODEFS'], { root: localPath }, vfsMountPoint);
 		return () => {
+			// TODO: Delete the mount point if was created during the mount.
 			FS!.unmount(vfsMountPoint);
 		};
 	};