Table constructor Null safety

Implementation

Table({
  super.key,
  this.children = const <TableRow>[],
  this.columnWidths,
  this.defaultColumnWidth = const FlexColumnWidth(),
  this.textDirection,
  this.border,
  this.defaultVerticalAlignment = TableCellVerticalAlignment.top,
  this.textBaseline, // NO DEFAULT: we don't know what the text's baseline should be
}) : assert(children != null),
     assert(defaultColumnWidth != null),
     assert(defaultVerticalAlignment != null),
     assert(defaultVerticalAlignment != TableCellVerticalAlignment.baseline || textBaseline != null, 'textBaseline is required if you specify the defaultVerticalAlignment with TableCellVerticalAlignment.baseline'),
     assert(() {
       if (children.any((TableRow row) => row.children == null)) {
         throw FlutterError(
           'One of the rows of the table had null children.\n'
           'The children property of TableRow must not be null.',
         );
       }
       return true;
     }()),
     assert(() {
       if (children.any((TableRow row) => row.children!.any((Widget cell) => cell == null))) {
         throw FlutterError(
           'One of the children of one of the rows of the table was null.\n'
           'The children of a TableRow must not be null.',
         );
       }
       return true;
     }()),
     assert(() {
       if (children.any((TableRow row1) => row1.key != null && children.any((TableRow row2) => row1 != row2 && row1.key == row2.key))) {
         throw FlutterError(
           'Two or more TableRow children of this Table had the same key.\n'
           'All the keyed TableRow children of a Table must have different Keys.',
         );
       }
       return true;
     }()),
     assert(() {
       if (children.isNotEmpty) {
         final int cellCount = children.first.children!.length;
         if (children.any((TableRow row) => row.children!.length != cellCount)) {
           throw FlutterError(
             'Table contains irregular row lengths.\n'
             'Every TableRow in a Table must have the same number of children, so that every cell is filled. '
             'Otherwise, the table will contain holes.',
           );
         }
       }
       return true;
     }()),
     _rowDecorations = children.any((TableRow row) => row.decoration != null)
                            ? children.map<Decoration?>((TableRow row) => row.decoration).toList(growable: false)
                            : null {
  assert(() {
    final List<Widget> flatChildren = children.expand<Widget>((TableRow row) => row.children!).toList(growable: false);
    if (debugChildrenHaveDuplicateKeys(this, flatChildren)) {
      throw FlutterError(
        'Two or more cells in this Table contain widgets with the same key.\n'
        'Every widget child of every TableRow in a Table must have different keys. The cells of a Table are '
        'flattened out for processing, so separate cells cannot have duplicate keys even if they are in '
        'different rows.',
      );
    }
    return true;
  }());
}