Noop provider does not have a rootPath set

src/backupformat/rsync.js

@@ -31,6 +31,9 @@ function getBackupFilePath(backupConfig, remotePath) {
     assert.strictEqual(typeof backupConfig, 'object');
     assert.strictEqual(typeof remotePath, 'string');
 
+    // we don't have a rootPath for noop
+    if (backupConfig.provider === 'noop') return remotePath;
+
     return path.join(backupConfig.rootPath, remotePath);
 }