DefaultTabController constructor Null safety
Creates a default tab controller for the given child widget.
The length argument is typically greater than one. The length must match TabBar.tabs's and TabBarView.children's length.
The initialIndex argument must not be null.
Implementation
const DefaultTabController({
super.key,
required this.length,
this.initialIndex = 0,
required this.child,
this.animationDuration,
}) : assert(initialIndex != null),
assert(length >= 0),
assert(length == 0 || (initialIndex >= 0 && initialIndex < length));