some refinement

internal/storage/file_store_test.go

@@ -21,12 +21,12 @@ func TestFileStore(t *testing.T) {
 	entry1 := websocket.HistoryEntry{
 		Type:      "logs",
 		Timestamp: 100,
-		Data:      map[string]interface{}{"msg": "hello world"},
+		Data:      json.RawMessage(`{"msg":"hello world"}`),
 	}
 	entry2 := websocket.HistoryEntry{
 		Type:      "traces",
 		Timestamp: 200,
-		Data:      map[string]interface{}{"msg": "trace event"},
+		Data:      json.RawMessage(`{"msg":"trace event"}`),
 	}
 
 	if err := fs.Append(ctx, entry1); err != nil {