Fixed: Improve logging for invalid NZB messages

Closes #2349

src/NzbDrone.Core/Download/InvalidNzbException.cs

@@ -20,10 +20,5 @@ namespace NzbDrone.Core.Download
         public InvalidNzbException(string message, Exception innerException) : base(message, innerException)
         {
         }
-
-        public InvalidNzbException(string message, string nzbName)
-            : base($"{message} [{0}]", nzbName)
-        {
-        }
     }
 }

src/NzbDrone.Core/Download/NzbValidationService.cs

@@ -24,12 +24,12 @@ namespace NzbDrone.Core.Download
 
                 if (nzb == null)
                 {
-                    throw new InvalidNzbException("No Root element", filename);
+                    throw new InvalidNzbException("Invalid NZB: No Root element [{0}]", filename);
                 }
 
                 if (!nzb.Name.LocalName.Equals("nzb"))
                 {
-                    throw new InvalidNzbException("Invalid root element", filename);
+                    throw new InvalidNzbException("Invalid NZB: Unexpected root element. Expected 'nzb' found '{0}' [{1}]", nzb.Name.LocalName, filename);
                 }
 
                 var ns = nzb.Name.Namespace;
@@ -37,7 +37,7 @@ namespace NzbDrone.Core.Download
 
                 if (files.Empty())
                 {
-                    throw new InvalidNzbException("No files", filename);
+                    throw new InvalidNzbException("Invalid NZB: No files [{0}]", filename);
                 }
             }
         }