message: GetAssignedExpressionFromDataDeclaration: check symbol tag
diff: @@ -1465,8 +1465,13 @@ static const SyntaxTreeNode* GetAssignedExpressionFromDataDeclaration(
  }
  if (!trailing_assign) return nullptr;
  - return &verible::GetSubtreeAsNode(*trailing_assign, NodeEnum::kTrailingAssign,
  - 1, NodeEnum::kExpression);
  + const verible::Symbol* expression = verible::GetSubtreeAsSymbol(
  + *trailing_assign, NodeEnum::kTrailingAssign, 1);
  + if (!expression ||
  + expression->Tag() != verible::NodeTag(NodeEnum::kExpression))
  + return nullptr;
  +
  + return &verible::SymbolCastToNode(*expression);
  }
  // This phase is strictly concerned with reshaping token partitions,
  