Fix index out of range issue in Powershell (#25681)

Author: veseshad92

src/Resources/Resources/ChangeLog.md

@@ -19,6 +19,7 @@
 -->
 
 ## Upcoming Release
+* Added null check and empty list check to the permissions object in the ToPSRoleDefinition method.
 * Added argument completer for `EnforcementMode`, `IdentityType`
     * `New-AzPolicyAssignment`
     * `New-AzPolicyExemption`

src/Resources/Resources/Models.Authorization/AuthorizationClientExtensions.cs

@@ -16,6 +16,7 @@
 using Microsoft.Azure.Commands.ActiveDirectory;
 using Microsoft.Azure.Management.Authorization.Models;
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
@@ -58,8 +59,8 @@ public static PSRoleDefinition ToPSRoleDefinition(this RoleDefinition role)
                     AssignableScopes = role.AssignableScopes.ToList(),
                     Description = role.Description,
                     IsCustom = role.RoleType == CustomRole ? true : false,
-                    Condition = role?.Permissions?[0]?.Condition,
-                    ConditionVersion = role?.Permissions?[0]?.ConditionVersion
+                    Condition = (role.Permissions != null && role.Permissions.Count > 0) ? role.Permissions[0].Condition : null,
+                    ConditionVersion = (role.Permissions != null && role.Permissions.Count > 0) ? role.Permissions[0].ConditionVersion : null
                 };
             }