Fix issue for PVS-Studio (#14372)

Author: Youri970410

src/Network/Network/Generated/LoadBalancer/BackendAddressPool/AddAzureRmLoadBalancerBackendAddressPoolConfigCommand.cs

@@ -52,19 +52,18 @@ public partial class AddAzureRmLoadBalancerBackendAddressPoolConfigCommand : Net
 
         public override void Execute()
         {
+            // BackendAddressPools
+            if (this.LoadBalancer.BackendAddressPools == null)
+            {
+                this.LoadBalancer.BackendAddressPools = new List<PSBackendAddressPool>();
+            }
 
             var existingBackendAddressPool = this.LoadBalancer.BackendAddressPools.SingleOrDefault(resource => string.Equals(resource.Name, this.Name, System.StringComparison.CurrentCultureIgnoreCase));
             if (existingBackendAddressPool != null)
             {
                 throw new ArgumentException("BackendAddressPool with the specified name already exists");
             }
 
-            // BackendAddressPools
-            if (this.LoadBalancer.BackendAddressPools == null)
-            {
-                this.LoadBalancer.BackendAddressPools = new List<PSBackendAddressPool>();
-            }
-
             var vBackendAddressPools = new PSBackendAddressPool();
 
             vBackendAddressPools.Name = this.Name;