Entity: Check if dbConn is nil before trying to return the connection

Signed-off-by: Michael Mayer <michael@photoprism.app>

internal/entity/db.go

@@ -15,6 +15,10 @@ func init() {
 
 // Db returns the default *gorm.DB connection.
 func Db() *gorm.DB {
+	if dbConn == nil {
+		return nil
+	}
+
 	return dbConn.Db()
 }