Return immediately if local ref update fails

Minor simplification, as in this case we don't need to enter the
try/catch block at all.

Change-Id: I8bc177f0e254488b7181d0ab02a43559209a61f1
diff --git a/src/main/java/com/gerritforge/gerrit/globalrefdb/validation/RefUpdateValidator.java b/src/main/java/com/gerritforge/gerrit/globalrefdb/validation/RefUpdateValidator.java
index 35ad560..a8047e6 100644
--- a/src/main/java/com/gerritforge/gerrit/globalrefdb/validation/RefUpdateValidator.java
+++ b/src/main/java/com/gerritforge/gerrit/globalrefdb/validation/RefUpdateValidator.java
@@ -190,10 +190,11 @@
       RefPair refPairForUpdate = newRefPairFrom(refUpdate);
       compareAndGetLatestLocalRef(refPairForUpdate, locks);
       RefUpdate.Result result = refUpdateFunction.invoke();
+      if (!isSuccessful(result)) {
+        return result;
+      }
       try {
-        if (isSuccessful(result)) {
-          updateSharedDbOrThrowExceptionFor(refPairForUpdate);
-        }
+        updateSharedDbOrThrowExceptionFor(refPairForUpdate);
       } catch (Exception e) {
         result = rollbackFunction.invoke(refPairForUpdate.compareRef.getObjectId());
         if (isSuccessful(result)) {