Update displayed error message for enterprise policies

cs/src/Management/TunnelManagementClient.cs

@@ -10,6 +10,7 @@
 using System.Net.Http;
 using System.Net.Http.Headers;
 using System.Security.Authentication;
+using System.Text.Json;
 
 #if NET5_0_OR_GREATER
 using System.Net.Http.Json;
@@ -690,12 +691,29 @@ private string UserLimitsPath
                         throw new ArgumentException(errorMessage, hrex);
 
                     case HttpStatusCode.Unauthorized:
-                    case HttpStatusCode.Forbidden:
-                        // Enterprise Policies
-                        if (response.Headers.Contains("X-Enterprise-Policy-Failure"))
-                        {
-                            var message = response.Content != null ? await response.Content.ReadAsStringAsync() : string.Empty;
-                            errorMessage = message;
+                    case HttpStatusCode.Forbidden:
+                        // Enterprise Policies
+                        if (response.Headers.Contains("X-Enterprise-Policy-Failure"))
+                        {
+                            var options = new JsonSerializerOptions
+                            {
+                                PropertyNameCaseInsensitive = true
+                            };
+                            var message = response.Content != null ? await response.Content.ReadAsStringAsync() : string.Empty;
+
+                            ErrorDetails? errorDetails = null;
+                            try
+                            {
+                                errorDetails = JsonSerializer.Deserialize<ErrorDetails>(message, options);
+                            }
+                            catch (JsonException)
+                            {
+                                // If deserialization fails, it means the message is not in JSON format.
+                                // In this case, use the message directly as the error message.
+                            }
+
+                            // Use the deserialized error detail if available, otherwise use the raw message.
+                            errorMessage = errorDetails?.Detail ?? message;
                         }
 
                         var ex = new UnauthorizedAccessException(errorMessage, hrex);
@@ -739,10 +757,11 @@ private string UserLimitsPath
         /// <remarks>
         /// Copied from Microsoft.VsSaaS.Common to avoid taking a dependency on that assembly.
         /// </remarks>
-        private class ErrorDetails
-        {
-            public string? Message { get; set; }
-            public string? StackTrace { get; set; }
+        private class ErrorDetails
+        {
+            public string? Message { get; set; }
+            public string? StackTrace { get; set; }
+            public string? Detail { get; set; }
         }
 
         /// <inheritdoc/>