removeLine method
Implementation
void removeLine({required BigInt lineIdx}) {
if (_root.summary.lines == 0) return;
_root.remove(lineIdx.toInt().clamp(0, _root.summary.lines - 1));
if (_root is _LayoutInternal &&
(_root as _LayoutInternal).children.isEmpty) {
_root = _LayoutLeaf();
}
while (_root is _LayoutInternal &&
(_root as _LayoutInternal).children.length == 1) {
_root = (_root as _LayoutInternal).children.single;
}
}