Fix use-of-uninit in eraseBetween (Node256)

ConflictSet.cpp

@@ -1874,7 +1874,7 @@ void eraseBetween(Node **inTree, Node256 *n, int begin, int end,
   const unsigned shiftAmount = begin;
   auto inBounds = [&](unsigned c) { return c - shiftAmount < shiftUpperBound; };
   n->numChildren = 0;
-  BitSet newBitSet;
+  BitSet newBitSet{};
   n->bitSet.forEachSet([&](int i) {
     if (inBounds(i)) {
       eraseTree(std::exchange(n->children[i], nullptr), tls);