fix: correct variable name in JSON unmarshal for site general information

internal/migrations/v30.go

diff --git a/internal/migrations/v30.go b/internal/migrations/v30.go
index a2dca77..72765e3 100644
--- a/internal/migrations/v30.go
+++ b/internal/migrations/v30.go
@@ -291,7 +291,7 @@
 		return err
 	}
 	oldSiteGeneral := &SiteGeneral{}
-	if err := json.Unmarshal([]byte(siteInfoLogin.Content), oldSiteGeneral); err != nil {
+	if err := json.Unmarshal([]byte(siteInfoGeneral.Content), oldSiteGeneral); err != nil {
 		return err
 	}