fix issues found by coverity scan tool

arangod/RocksDBEngine/RocksDBEdgeIndex.cpp

@@ -267,7 +267,6 @@ bool RocksDBEdgeIndexIterator::nextExtra(ExtraCallback const& cb,
           _builderIterator = VPackArrayIterator(
               arangodb::basics::VelocyPackHelper::EmptyArrayValue());
         } else {
-          _copyCounter++;
           // We need to copy it.
           // And then we just get back to beginning of the loop
           _builder.clear();

arangod/RocksDBEngine/RocksDBEdgeIndex.h

@@ -77,8 +77,6 @@ class RocksDBEdgeIndexIterator final : public IndexIterator {
   std::shared_ptr<cache::Cache> _cache;
   arangodb::velocypack::ArrayIterator _builderIterator;
   arangodb::velocypack::Builder _builder;
-  size_t _copyCounter;
-  size_t _lookupCounter;
 };
 
 class RocksDBEdgeIndex final : public RocksDBIndex {

arangod/RocksDBEngine/RocksDBReplicationTailing.cpp

@@ -80,8 +80,8 @@ class WALParser : public rocksdb::WriteBatch::Handler {
         _includeSystem(includeSystem),
         _onlyCollectionId(collectionId),
         _builder(builder),
-        _currentSequence(0)
-         {}
+        _startSequence(0),
+        _currentSequence(0) {}
 
   void LogData(rocksdb::Slice const& blob) override {
     RocksDBLogType type = RocksDBLogValue::type(blob);

arangod/RocksDBEngine/RocksDBRestReplicationHandler.cpp

@@ -439,15 +439,7 @@ void RocksDBRestReplicationHandler::handleCommandBatch() {
 
     _vocbase->updateReplicationClient(serverId, ctx->lastTick());
 
-    // now extend the blocker
-    // StorageEngine* engine = EngineSelectorFeature::ENGINE;
-    // res = engine->extendCompactionBlocker(_vocbase, id, expires);
-
-    if (res == TRI_ERROR_NO_ERROR) {
-      resetResponse(rest::ResponseCode::NO_CONTENT);
-    } else {
-      generateError(GeneralResponse::responseCode(res), res);
-    }
+    resetResponse(rest::ResponseCode::NO_CONTENT);
     return;
   }