src/vs/platform/files/common/inMemoryFilesystemProvider.ts/InMemoryFileSystemProvider/readFile
class InMemoryFileSystemProvider:	async readFile(resource: URI): Promise<Uint8Array> {
		const data = this._lookupAsFile(resource, false).data;
		if (data) {
			return data;
		}
		throw new FileSystemProviderError('file not found', FileSystemProviderErrorCode.FileNotFound);
	}