Fix malformed query when user with no access to any financial acls ac…

…cesses civimember search

ext/financialacls/financialacls.php

@@ -229,7 +229,7 @@ function _financialacls_civicrm_get_membership_type_clause(): string {
   }
   $financialTypes = _financialacls_civicrm_get_accessible_financial_types();
   if ($financialTypes === [0]) {
-    return 0;
+    return '= 0';
   }
   $membershipTypes = (array) MembershipType::get(FALSE)
     ->addWhere('financial_type_id', 'IN', $financialTypes)->execute()->indexBy('id');