src/vs/platform/files/common/fileService.ts/FileService/readFileStreamed
class FileService:	private readFileStreamed(provider: IFileSystemProviderWithFileReadStreamCapability, resource: URI, token: CancellationToken, options: IReadFileStreamOptions = Object.create(null)): VSBufferReadableStream {
		const fileStream = provider.readFileStream(resource, options, token);

		return transform(fileStream, {
			data: data => data instanceof VSBuffer ? data : VSBuffer.wrap(data),
			error: error => new FileOperationError(localize('err.read', "Unable to read file '{0}' ({1})", this.resourceForError(resource), ensureFileSystemProviderError(error).toString()), toFileOperationResult(error), options)
		}, data => VSBuffer.concat(data));
	}