investigate SO62732593; add some error detail to TryGetClientHelper

Author: mgravell

src/protobuf-net.Grpc/Internal/ContractOperation.cs

@@ -286,9 +286,17 @@ public static List<ContractOperation> FindOperations(BinderConfiguration binderC
 
         internal MethodInfo? TryGetClientHelper()
         {
+
             var name = GetClientHelperName();
-            if (name == null || !s_reshaper.TryGetValue(name, out var method)) return null;
-            return method.MakeGenericMethod(From, To);
+            try
+            {
+                if (name == null || !s_reshaper.TryGetValue(name, out var method)) return null;
+                return method.MakeGenericMethod(From, To);
+            }
+            catch (Exception ex)
+            {
+                throw new InvalidOperationException($"Error obtaining client-helper '{name}' (from: '{From?.FullName}', to: '{To?.FullName}'): {ex.Message}", ex);
+            }
         }
 #pragma warning disable CS0618 // Reshape
         static readonly Dictionary<string, MethodInfo> s_reshaper =

tests/protobuf-net.Grpc.Test.Integration/Issues/SO62732593.cs

@@ -0,0 +1,44 @@
+using Grpc.Core;
+using ProtoBuf.Grpc.Client;
+using System.Collections.Generic;
+using System.Runtime.Serialization;
+using System.ServiceModel;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace protobuf_net.Grpc.Test.Integration.Issues
+{
+    public class SO62732593
+    {
+        [Fact]
+        public void CanCreateProxy()
+        {
+            Channel channel = new Channel("none", ChannelCredentials.Insecure);
+            var svc = channel.CreateGrpcService<ICustomerService>();
+            Assert.NotNull(svc);
+        }
+
+        [DataContract]
+        public class CustomerResultSet
+        {
+            [DataMember(Order = 1)]
+            public IEnumerable<Customer> Customers { get; set; }
+        }
+        [DataContract]
+        public partial class Customer
+        {
+            [DataMember(Order = 1)]
+            public int CustomerId { get; set; }
+            [DataMember(Order = 2)]
+            public string CustomerName { get; set; }
+        }
+
+        [ServiceContract(Name = "Services.Customer")]
+        public interface ICustomerService
+        {
+            ValueTask<Customer> CreateCustomer(Customer customerDTO);
+
+            ValueTask<CustomerResultSet> GetCustomers();
+        }
+    }
+}