message: Follow-up to don't return address of stack variable
diff: @@ -99,7 +99,7 @@ public:
  virtual idx_t NumColumns() = 0;
  virtual const string &ColumnName(idx_t col) = 0;
  virtual const LogicalType &ColumnType(idx_t col) = 0;
  - virtual const char *ColumnDefault(idx_t col) = 0;
  + virtual const Value ColumnDefault(idx_t col) = 0;
  virtual bool IsNullable(idx_t col) = 0;
  void WriteColumns(idx_t index, idx_t start_col, idx_t end_col, DataChunk &output);
  @@ -128,11 +128,11 @@ public:
  const LogicalType &ColumnType(idx_t col) {
  return entry->columns[col].type;
  }
  - const char *ColumnDefault(idx_t col) {
  + const Value ColumnDefault(idx_t col) {
  if (entry->columns[col].default_value) {
  - return entry->columns[col].default_value->ToString().c_str();
  + return Value(entry->columns[col].default_value->ToString());
  }
  - return nullptr;
  + return Value();
  }
  bool IsNullable(idx_t col) {
  return not_null_cols.find(col) == not_null_cols.end();
  @@ -160,8 +160,8 @@ public:
  const LogicalType &ColumnType(idx_t col) {
  return entry->types[col];
  }
  - const char *ColumnDefault(idx_t col) {
  - return nullptr;
  + const Value ColumnDefault(idx_t col) {
  + return Value();
  }
  bool IsNullable(idx_t col) {
  return true;
  