fix: stabilize im server startup and p2p topic scans

server/store/types/default_access_test.go

@@ -0,0 +1,30 @@
+package types
+
+import "testing"
+
+func TestDefaultAccessScanAllowsNil(t *testing.T) {
+	var da DefaultAccess
+	if err := da.Scan(nil); err != nil {
+		t.Fatalf("Scan(nil) returned error: %v", err)
+	}
+	if da.Auth != ModeNone || da.Anon != ModeNone {
+		t.Fatalf("Scan(nil) changed default access: %#v", da)
+	}
+}
+
+func TestDefaultAccessScanJSON(t *testing.T) {
+	for name, input := range map[string]any{
+		"bytes":  []byte(`{"Auth":"JRWP","Anon":"N"}`),
+		"string": `{"Auth":"JRWP","Anon":"N"}`,
+	} {
+		t.Run(name, func(t *testing.T) {
+			var da DefaultAccess
+			if err := da.Scan(input); err != nil {
+				t.Fatalf("Scan returned error: %v", err)
+			}
+			if da.Auth.String() != "JRWP" || da.Anon.String() != "N" {
+				t.Fatalf("unexpected default access: %#v", da)
+			}
+		})
+	}
+}

server/store/types/types.go

@@ -863,7 +863,17 @@ type DefaultAccess struct {
 // Scan is an implementation of Scanner interface so the value can be read from SQL DBs
 // It assumes the value is serialized and stored as JSON
 func (da *DefaultAccess) Scan(val any) error {
-	return json.Unmarshal(val.([]byte), da)
+	if val == nil {
+		return nil
+	}
+	switch v := val.(type) {
+	case []byte:
+		return json.Unmarshal(v, da)
+	case string:
+		return json.Unmarshal([]byte(v), da)
+	default:
+		return errors.New("scan failed: data is not a byte slice or string")
+	}
 }
 
 // Value implements sql's driver.Valuer interface.