The method 'toDouble' was called on null.

[JatinJD14296]

The method 'toDouble' was called on null.
Receiver: null
Tried calling: toDouble()

The relevant error-causing widget was:
CollapsibleSidebar file:///Users/imac/Documents/workspace/fittrack_flutter/lib/features/home/presentation/pages/home_screen.dart:48:21
When the exception was thrown, this was the stack:
#0 Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1 double.* (dart:core-patch/double.dart:36:23)
#2 _CollapsibleSidebarState.build (package:collapsible_sidebar/collapsible_sidebar.dart:177:46)
#3 StatefulElement.build (package:flutter/src/widgets/framework.dart:4681:28)
#4 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4564:15)
...

ERROR MOVE ON THIS LINE...

Stack(
alignment: Alignment.topCenter,
children: [
CollapsibleItemSelection(
height: _maxOffsetY,
======> offsetY: _maxOffsetY * _selectedItemIndex,
color: widget.selectedIconBox,
duration: widget.duration,
curve: widget.curve,
),
Column(children: _items),
],
),

[DrunkOnBytes]

Please send entire code where the error occurs.

[dariolr]

I had the same problem, maybe depend on the way you build CollapsibleItem list.

in my case...

List<CollapsibleItem> _buildCollapsibleItems(List<String> menuNames) {
    final List<CollapsibleItem> result = [];
    menuNames.asMap().forEach((index, value) => {
          result.add(CollapsibleItem(
              isSelected: _selectedIndex == index,
              text: value,
              icon: _iconByMenuName(value),
              onPressed: () => setState(() {
                    _headline = value;
                    _selectedIndex = index;
                  })))
        });

    return result;
}

_selectedIndex is set to zero on initState

[ReniDelonzek]

I have the same issue. Any solution?

[DrunkOnBytes]

Can you guys send the code and the line number as shown by the terminal where the error is occurring. @dariolr @ReniDelonzek

I'll try to see where this exception is coming from.

[ReniDelonzek]

Hello @RyuuKenshi , the error happens when no item is pre-selected. I fixed this on my fork, but I didn't submit it because I did a few more increments that may not be relevant here. But set _selectedItemIndex = 0; in initState should resolve

[DrunkOnBytes]

Hi @JatinJD14296, @dariolr, @ReniDelonzek, I have implemented some changes to this package.
Please check once if this problem has been resolved, and if yes then close this issue.