SplitPane: RangeError when rebuilding with a different number of children

[rrousselGit]

Here's extracted code from my devtool extension:

SplitPane(
  axis: .vertical,
  initialFractions: [
    state.fraction,
    ?notifier?.fraction,
    terminal.fraction,
  ],
  minSizes: [state.minSize, ?notifier?.minSize, terminal.minSize],
  splitters: [if (notifier != null) notifier.heading, terminal.heading],
  children: [state.content, ?notifier?.content, terminal.content],
),

When notifier changes between != null and null, the following error is thrown:

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following IndexError was thrown building LayoutBuilder:
RangeError (index): Index out of range: index should be less than 2: 2

The relevant error-causing widget was:
  SplitPane
  SplitPane:file:///Users/remirousselet/dev/rrousselGit/riverpod/packages/riverpod_devtool/lib/src/frame_view.dart:189:14

When the exception was thrown, this was the stack:
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 274:3       throw_
errors.dart:274
dart-sdk/lib/_internal/js_dev_runtime/private/js_array.dart 608:7                 _get]
js_array.dart:608
package:devtools_app_shared/src/ui/split_pane.dart 126:20                         minSizeForIndex
split_pane.dart:126
package:devtools_app_shared/src/ui/split_pane.dart 130:9                          minFractionForIndex
split_pane.dart:130
package:devtools_app_shared/src/ui/split_pane.dart 143:28                         deltaFromMinimumSize
split_pane.dart:143
package:devtools_app_shared/src/ui/split_pane.dart 146:21                         [_buildLayout]
split_pane.dart:146
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 118:77  tear
operations.dart:118
package:flutter/src/widgets/layout_builder.dart 232:67                            updateChildCallback
layout_builder.dart:232
package:flutter/src/widgets/framework.dart 3101:11                                buildScope
framework.dart:3101
package:flutter/src/widgets/layout_builder.dart 270:5                             [_rebuildWithConstraints]
layout_builder.dart:270
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 118:77  tear
operations.dart:118
package:flutter/src/widgets/layout_builder.dart 333:28                            layoutCallback
layout_builder.dart:333
package:flutter/src/rendering/object.dart 4162:33                                 <fn>
object.dart:4162
package:flutter/src/rendering/object.dart 2887:9                                  <fn>
object.dart:2887
package:flutter/src/rendering/object.dart 1223:7                                  [_enableMutationsToDirtySubtrees]
object.dart:1223
package:flutter/src/rendering/object.dart 2886:7                                  invokeLayoutCallback
object.dart:2886
package:flutter/src/rendering/object.dart 4162:5                                  runLayoutCallback
object.dart:4162
package:flutter/src/widgets/layout_builder.dart 447:5                             performLayout
layout_builder.dart:447
package:flutter/src/rendering/object.dart 2616:7                                  [_layoutWithoutResize]
object.dart:2616
package:flutter/src/rendering/object.dart 1174:17                                 flushLayout
object.dart:1174
package:flutter/src/rendering/object.dart 1187:14                                 flushLayout
object.dart:1187
package:flutter/src/rendering/binding.dart 629:5                                  drawFrame
binding.dart:629
package:flutter/src/widgets/binding.dart 1269:13                                  drawFrame
binding.dart:1269
package:flutter/src/rendering/binding.dart 495:5                                  [_handlePersistentFrameCallback]
binding.dart:495
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 118:77  tear
operations.dart:118
package:flutter/src/scheduler/binding.dart 1430:7                                 [_invokeFrameCallback]
binding.dart:1430
package:flutter/src/scheduler/binding.dart 1345:9                                 handleDrawFrame
binding.dart:1345
package:flutter/src/scheduler/binding.dart 1198:5                                 [_handleDrawFrame]
binding.dart:1198
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 118:77  tear
operations.dart:118
lib/_engine/engine/platform_dispatcher.dart 1700:5                                invoke
platform_dispatcher.dart:1700
lib/_engine/engine/platform_dispatcher.dart 268:5                                 invokeOnDrawFrame
platform_dispatcher.dart:268
lib/_engine/engine/frame_service.dart 209:32                                      [_renderFrame]
frame_service.dart:209
lib/_engine/engine/frame_service.dart 117:9                                       <fn>
frame_service.dart:117
dart-sdk/lib/async/zone_root.dart 56:13                                           _rootRunUnary
zone_root.dart:56
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 118:77  tear
operations.dart:118
dart-sdk/lib/async/zone.dart 733:19                                               runUnary
zone.dart:733
dart-sdk/lib/async/zone.dart 654:26                                               <fn>
zone.dart:654
dart-sdk/lib/_internal/js_dev_runtime/patch/js_allow_interop_patch.dart 224:27    _callDartFunctionFast1
js_allow_interop_patch.dart:224
dart-sdk/lib/_internal/js_dev_runtime/patch/js_allow_interop_patch.dart 84:15     ret
js_allow_interop_patch.dart:84

[rrousselGit]

I have temporarily added a key on the object to forcibly unmount/remount the widget when notifier changes between null and non-null.

This works around the error