added exception logging to Tasks.

NzbDrone.Common/TPL/TaskExtensions.cs

@@ -0,0 +1,25 @@
+using System.Threading.Tasks;
+using NLog;
+
+namespace NzbDrone.Common.TPL
+{
+    public static class TaskExtensions
+    {
+        private static readonly Logger Logger = LogManager.GetLogger("TaskExtensions");
+
+        public static Task LogExceptions(this Task task)
+        {
+            task.ContinueWith(t =>
+                {
+                    var aggregateException = t.Exception.Flatten();
+                    foreach (var exception in aggregateException.InnerExceptions)
+                    {
+                        Logger.ErrorException("Task Error", exception);
+                    }
+
+                }, TaskContinuationOptions.OnlyOnFaulted);
+
+            return task;
+        }
+    }
+}