Call GetRequiredService when creating Workspace in order to get exception in...

Call GetRequiredService when creating Workspace in order to get exception in case a service is missing.

src/Workspaces/Core/Portable/Workspace/Host/HostWorkspaceServices.cs

@@ -38,7 +38,7 @@ public abstract class HostWorkspaceServices
             var service = GetService<TWorkspaceService>();
             if (service == null)
             {
-                throw new InvalidOperationException(WorkspacesResources.WorkspaceServicesUnavailable);
+                throw new InvalidOperationException(string.Format(WorkspacesResources.WorkspaceServicesUnavailable, typeof(TWorkspaceService).FullName));
             }
 
             return service;

src/Workspaces/Core/Portable/Workspace/Workspace.cs

@@ -59,7 +59,7 @@ protected Workspace(HostServices host, string workspaceKind)
             _services = host.CreateWorkspaceServices(this);
 
             // queue used for sending events
-            var workspaceTaskSchedulerFactory = _services.GetService<IWorkspaceTaskSchedulerFactory>();
+            var workspaceTaskSchedulerFactory = _services.GetRequiredService<IWorkspaceTaskSchedulerFactory>();
             _taskQueue = workspaceTaskSchedulerFactory.CreateTaskQueue();
 
             // initialize with empty solution

src/Workspaces/Core/Portable/WorkspacesResources.Designer.cs

@@ -1079,7 +1079,7 @@ internal class WorkspacesResources {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Services required to accomplish the task are not available from the workspace..
+        ///   Looks up a localized string similar to Service of type &apos;{0}&apos; is required to accomplish the task but is not available from the workspace..
         /// </summary>
         internal static string WorkspaceServicesUnavailable {
             get {

src/Workspaces/Core/Portable/WorkspacesResources.resx

@@ -397,7 +397,7 @@
     <value>Removing project references is not supported.</value>
   </data>
   <data name="WorkspaceServicesUnavailable" xml:space="preserve">
-    <value>Services required to accomplish the task are not available from the workspace.</value>
+    <value>Service of type '{0}' is required to accomplish the task but is not available from the workspace.</value>
   </data>
   <data name="DiagnosticCannotBeNull" xml:space="preserve">
     <value>Supplied diagnostic cannot be null.</value>