I’m writing a Flutter app and running it on the desktop. One of its pages has a column with the following widget as the first child:

class HeroBanner extends StatelessWidget {
  String? image;
  String title = "";
  double maxHeight = 400;

  HeroBanner({Key? key, this.image, this.title = "", this.maxHeight = 100});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return image != null
        ? LayoutBuilder(builder: (context, constraints) {
            return ClipRect(
              clipBehavior: Clip.hardEdge,
              child: SizedBox(
                height: maxHeight,
                child: Stack(
                  children: [
                    SizedBox(
                        width: MediaQuery.of(context).size.width,
                        child: FittedBox(
                            fit: BoxFit.cover, 
                            child: Image.asset(image!))),
                    const FadeToBlackFilter(),
                    Align(
                      alignment: Alignment.bottomLeft,
                      child: Padding(
                        padding: comfortable,
                        child: Text(
                          title,
                          overflow: TextOverflow.ellipsis,
                          style:
                              pageTitle(context).copyWith(color: Colors.white),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            );
          })
        : PageTitle(title);
  }
}

Showing this widget makes the app not responsive to mouse events. The widget is correctly shown as far as I can see and the app is still updating (e.g. resizing still updates the widgets). When I check the debug console I see the following:

════════ Exception caught by rendering library ═════════════════════════════════
'package:flutter/src/rendering/box.dart': Failed assertion: line 327 pos 12: 'width > 0.0': is not true.
The relevant error-causing widget was:
════════════════════════════════════════════════════════════════════════════════

════════ Exception caught by rendering library ═════════════════════════════════
RenderBox was not laid out: RenderFittedBox#abf19 relayoutBoundary=up22 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
'package:flutter/src/rendering/box.dart':
Failed assertion: line 2165 pos 12: 'hasSize'
The relevant error-causing widget was:
════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by scheduler library ═════════════════════════════════
'package:flutter/src/rendering/mouse_tracker.dart': Failed assertion: line 200 pos 12: '!_debugDuringDeviceUpdate': is not true.
════════════════════════════════════════════════════════════════════════════════

I’m at a loss at what could be the culprit.

I’ve tried wrapping the widget in sized bounds, including Expanded() (which made the whole thing not render at all), SizedBox() with defined width and height (also does not render) and adding a DebugBorder() (a container with red border) to see where the widget’s borders are (correctly extends to the width of the screen and finite height only). However, the widget does not seem to be of the height specified (i.e. not 400, and I did not override it).