Handle `??` operator precedence

[vlastachu]

It is common way to write widget which can optionally take controller as its own property.

You should handle null case for such controller in initState or lazy variable declaration:

  late final _controller =
        widget.controller ?? TextEditingController(text: widget.initialValue);

lint suggest you next rewriting:

  late final _controller =
        widget.controller ?? TextEditingController(text: widget.initialValue).closeWith(this);

which you can read as

  late final _controller =
        widget.controller ?? (TextEditingController(text: widget.initialValue).closeWith(this));

but it is actually

  late final _controller =
        (widget.controller ?? TextEditingController(text: widget.initialValue)).closeWith(this);

So in case when widget's property controller is not null it will possibly closed sooner than it should.