Added test.

src/DynamoCoreWpf/ViewModels/PackageManager/PublishPackageViewModel.cs

@@ -538,7 +538,8 @@ internal PublishPackageViewModel()
 
         private void BeginInvoke(Action action)
         {
-            if (dynamoViewModel != null)
+            // dynamoViewModel.UIDispatcher can be null in unit tests.
+            if (dynamoViewModel != null && dynamoViewModel.UIDispatcher != null)
                 dynamoViewModel.UIDispatcher.BeginInvoke(action);
         }
 
@@ -606,7 +607,7 @@ public static PublishPackageViewModel FromLocalPackage(DynamoViewModel dynamoVie
 
                 switch (result)
                 {
-                    case AssemblyLoadingState.Succes:
+                    case AssemblyLoadingState.Success:
                         {
                             var isNodeLibrary = nodeLibraryNames == null || nodeLibraryNames.Contains(assem.FullName);
                             vm.Assemblies.Add(new PackageAssembly()

src/DynamoPackages/PackageLoader.cs

@@ -21,7 +21,7 @@ public struct LoadPackageParams
 
     public enum AssemblyLoadingState
     {
-        Succes,
+        Success,
         NotManagedAssembly,
         AlreadyLoaded
     }
@@ -243,13 +243,13 @@ public Package ScanPackageDirectory(string directory)
         /// </summary>
         /// <param name="filename">The filename of a DLL</param>
         /// <param name="assem">out Assembly - the passed value does not matter and will only be set if loading succeeds</param>
-        /// <returns>Returns Succes if success, NotManagedAssembly if BadImageFormatException, AlreadyLoaded if FileLoadException</returns>
+        /// <returns>Returns Success if success, NotManagedAssembly if BadImageFormatException, AlreadyLoaded if FileLoadException</returns>
         internal static AssemblyLoadingState TryReflectionOnlyLoadFrom(string filename, out Assembly assem)
         {
             try
             {
                 assem = Assembly.ReflectionOnlyLoadFrom(filename);
-                return AssemblyLoadingState.Succes;
+                return AssemblyLoadingState.Success;
             }
             catch (BadImageFormatException)
             {

test/DynamoCoreWpfTests/PublishPackageViewModelTests.cs

@@ -74,5 +74,26 @@ public void SetsErrorState()
 
         }
 
+
+        [Test]
+        public void NewPackageVersionUpload_DoesNotThrowExceptionWhenDLLIsLoadedSeveralTimes()
+        {
+            string packagesDirectory = Path.Combine(TestDirectory, "pkgs");
+
+            var loader = new PackageLoader(packagesDirectory);
+            loader.LoadAll(new LoadPackageParams
+            {
+                Preferences = ViewModel.Model.PreferenceSettings
+            });
+
+            PublishPackageViewModel vm = null;
+            Assert.DoesNotThrow(() =>
+            {
+                vm = PublishPackageViewModel.FromLocalPackage(ViewModel, loader.LocalPackages.First());
+            });
+
+            Assert.AreEqual(PackageUploadHandle.State.Error, vm.UploadState);
+        }
+
     }
 }