childMaxVersion memory needs to be defined

Also remove some dead code, and only memset children to 0 for Node256.
Other nodes detect absence of children other ways.

ConflictSet.cpp

@@ -692,16 +692,6 @@ static_assert(kBytesPerKey - sizeof(Node0) >= kMinNodeSurplus);
 // Which should give us the budget to pay for the key bytes. (children +
 // entryPresent) is a lower bound on how many keys these bytes are a prefix of
 
-constexpr int getMaxCapacity(int numChildren, int entryPresent,
-                             int partialKeyLen) {
-  return (numChildren + entryPresent) * (partialKeyLen + 1);
-}
-
-constexpr int getMaxCapacity(Node *self) {
-  return getMaxCapacity(self->numChildren, self->entryPresent,
-                        self->partialKeyLen);
-}
-
 template <class T> struct NodeAllocator {
 
   static_assert(std::derived_from<T, Node>);
@@ -712,12 +702,14 @@ template <class T> struct NodeAllocator {
     result->endOfRange = false;
     result->releaseDeferred = false;
     if constexpr (!std::is_same_v<T, Node0>) {
-      memset(result->children, 0, sizeof(result->children));
       const auto z = InternalVersionT::zero;
       for (auto &v : result->childMaxVersion) {
         v = z;
       }
     }
+    if constexpr (std::is_same_v<T, Node256>) {
+      memset(result->children, 0, sizeof(result->children));
+    }
     if constexpr (std::is_same_v<T, Node48> || std::is_same_v<T, Node256>) {
       const auto z = InternalVersionT::zero;
       for (auto &v : result->maxOfMax) {
@@ -1973,8 +1965,6 @@ Node *erase(Node *self, WriteContext *writeContext, ConflictSet::Impl *impl,
                                 sizeof(parent3->index[0]));
     VALGRIND_MAKE_MEM_UNDEFINED(parent3->children + parent3->numChildren,
                                 sizeof(parent3->children[0]));
-    VALGRIND_MAKE_MEM_UNDEFINED(parent3->childMaxVersion + parent3->numChildren,
-                                sizeof(parent3->childMaxVersion[0]));
 
     if (needsDownsize(parent3)) {
       downsize(parent3, writeContext, impl);
@@ -1994,9 +1984,6 @@ Node *erase(Node *self, WriteContext *writeContext, ConflictSet::Impl *impl,
                                 sizeof(parent16->index[0]));
     VALGRIND_MAKE_MEM_UNDEFINED(parent16->children + parent16->numChildren,
                                 sizeof(parent16->children[0]));
-    VALGRIND_MAKE_MEM_UNDEFINED(parent16->childMaxVersion +
-                                    parent16->numChildren,
-                                sizeof(parent16->childMaxVersion[0]));
 
     if (needsDownsize(parent16)) {
       downsize(parent16, writeContext, impl);