add null check

Author: DeepakRajendranMsft

src/ResourceManager/Network/Commands.Network/NetworkInterface/NetworkInterfaceBaseCmdlet.cs

@@ -79,6 +79,11 @@ public PSNetworkInterface GetScaleSetNetworkInterface(string resourceGroupName,
 
 		public void NullifyApplicationSecurityGroupIfAbsent(NetworkInterface nic)
 		{
+			if (nic.IpConfigurations == null)
+			{
+				return;
+			}
+
 			// Temporary - to be removed
 			foreach (var ipconfigModel in nic.IpConfigurations)
 			{

src/ResourceManager/Network/Commands.Network/NetworkSecurityGroup/NetworkSecurityGroupBaseCmdlet.cs

@@ -67,6 +67,11 @@ public PSNetworkSecurityGroup GetNetworkSecurityGroup(string resourceGroupName,
 		// Temporary - to be removed
 		public void NullifyApplicationSecurityGroupsIfAbsent(NetworkSecurityGroup nsg)
 		{
+			if (nsg.SecurityRules == null)
+			{
+				return;
+			}
+
 			foreach (var rule in nsg.SecurityRules)
 			{
 				if (rule.SourceApplicationSecurityGroups != null && rule.SourceApplicationSecurityGroups.Count == 0)