message: verilog: formatting: tree_unwrapper: Fixed symbol cast check failure
  Fixed a case of trying to cast a preprocessor's operator (a leaf) as a
  Node, where it causes a check failure and a hard crash. Added another
  check to see if the whether the casted part is a leaf
diff: @@ -2970,7 +2970,8 @@ void TreeUnwrapper::ReshapeTokenPartitions(
  // In these cases, merge the 'begin' partition of the statement block
  // with the preceding keyword or header partition.
  - if (NodeIsBeginEndBlock(
  + if (!verible::is_leaf(partition.Children().back()) &&
  + NodeIsBeginEndBlock(
  verible::SymbolCastToNode(*node.children().back()))) {
  auto& seq_block_partition = partition.Children().back();
  VLOG(4) << "block partition: " << seq_block_partition;
  