Damaged assets, especially appearance textures, could crash the region server with a fatal exception.

Now, such excpetions are caught by an exception handler and just an error message is shown.
This was the kind of exception causing these fatal server crashes:

  APPLICATION EXCEPTION DETECTED: System.UnhandledExceptionEventArgs^M
  ^M
  Exception: System.ArgumentOutOfRangeException: Argument is out of range.
  Parameter name: offset exceeds the size of buffer
    at System.Net.Sockets.NetworkStream.BeginRead (System.Byte[] buffer, Int32 offset, Int32 size, System.AsyncCallback callback, System.Object state) [0x00000] in <filename unknown>:0
    at HttpServer.HttpClientContext.OnReceive (IAsyncResult ar) [0x00000] in <filename unknown>:0 ^M
  ^M
  Application is terminating: True^M

OpenSim/Services/AssetService/AssetService.cs

@@ -117,7 +117,15 @@ namespace OpenSim.Services.AssetService
                 return null;
             }
 
-            return m_Database.GetAsset(assetID);
+            try
+            {
+                return m_Database.GetAsset(assetID);
+            }
+            catch (Exception e)
+            {
+                m_log.ErrorFormat("[ASSET SERVICE]: Exception getting asset {0} {1}", assetID, e);
+                return null;
+            }
         }
 
         public virtual AssetBase GetCached(string id)