Ref #33886: fix null access-control

Author: LEDfan

src/main/java/eu/openanalytics/containerproxy/service/AccessControlEvaluationService.java

@@ -71,7 +71,7 @@ public boolean checkAccess(Authentication auth, ProxySpec spec, AccessControl ac
             return contextBuilder.build();
         });
 
-        if (accessControl.hasStrictExpressionAccess()) {
+        if (accessControl != null && accessControl.hasStrictExpressionAccess()) {
             // strict expression is always checked
             if (!specExpressionResolver.evaluateToBoolean(accessControl.getStrictExpression(), context.get())) {
                 // not allowed by strict expression