diff --git a/server/services/datasource-service.js b/server/services/datasource-service.js
index 9850adc..5c31bb4 100644
--- a/server/services/datasource-service.js
+++ b/server/services/datasource-service.js
@@ -102,10 +102,10 @@ class MockAdapter extends DataSourceAdapter {
 // ════════════════════════════════════════
 
 class FileAdapter extends DataSourceAdapter {
-  constructor(config) {
+  constructor(config = {}) {
     super(config);
     this.name = 'file';
-    this.dataDir = config.dataDir || path.join(DATA_DIR, '_datasources');
+    this.dataDir = (config && config.dataDir) || path.join(DATA_DIR, '_datasources');
   }
 
   async fetchMetrics({ startDate, endDate }) {