src/vs/platform/files/browser/htmlFileSystemProvider.ts/HTMLFileSystemProvider/getFileHandle
class HTMLFileSystemProvider:	private async getFileHandle(resource: URI): Promise<FileSystemFileHandle | undefined> {
		const handle = await this.doGetHandle(resource);
		if (handle instanceof FileSystemFileHandle) {
			return handle;
		}

		const parent = await this.getDirectoryHandle(this.extUri.dirname(resource));

		try {
			return await parent?.getFileHandle(extUri.basename(resource));
		} catch (error) {
			return undefined; // guard against possible DOMException
		}
	}