Fix user profile writes on postgres conflicts

backend/internal/service/sql_errors.go

@@ -0,0 +1,14 @@
+package service
+
+import (
+	"database/sql"
+	"errors"
+	"strings"
+)
+
+func isSQLNoRowsError(err error) bool {
+	if err == nil {
+		return false
+	}
+	return errors.Is(err, sql.ErrNoRows) || strings.Contains(err.Error(), "no rows in result set")
+}