Improve RDE error logging

RDE logs somewhat inscrutable errors when XML validation of the output fails due to bad data in Datastore. This CL adds a little more information to help us track down this sort of problem in the future.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=140872462

java/google/registry/rde/RdeMarshaller.java

@@ -148,7 +148,7 @@ public final class RdeMarshaller implements Serializable {
           Key.create(resource),
           e.getLinkedException(),
           getMarshaller().marshalLenient(element));
-      logger.severe(error);
+      logger.severe(e, error);
     }
     return DepositFragment.create(type, xml, error);
   }

java/google/registry/rde/RdeStagingReducer.java

@@ -162,7 +162,7 @@ public final class RdeStagingReducer extends Reducer<PendingDeposit, DepositFrag
     }
 
     // If an entity was broken, abort after writing as much logs/deposit data as possible.
-    verify(!failed);
+    verify(!failed, "RDE staging failed for TLD %s", tld);
 
     // Write a file to GCS containing the byte length (ASCII) of the raw unencrypted XML.
     //