src/vs/workbench/api/common/extHostFileSystem.ts/ExtHostFileSystem/$close
class ExtHostFileSystem:	$close(handle: number, fd: number): Promise<void> {
		const provider = this._getFsProvider(handle);
		if (!provider.close) {
			throw new Error('FileSystemProvider does not implement "close"');
		}
		return Promise.resolve(provider.close(fd));
	}