Index out of range error when changing the graph object

[emmby]

The following IndexError was thrown building _GraphViewAnimated(dirty, dependencies: [MediaQuery],
state: _GraphViewAnimatedState#68d80):
RangeError (index): Index out of range: index should be less than 8: 8

The relevant error-causing widget was:
  GraphView$ GraphView:file:///Users/mike/Documents/GitHub/kgng/lib/src/home/node_view.dart:219:20

When the exception was thrown, this was the stack:
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 294:3       throw_
dart-sdk/lib/_internal/js_dev_runtime/private/js_array.dart 600:7                 _get]
packages/graphview/GraphView.dart 299:34                                          <fn>
dart-sdk/lib/_internal/js_dev_runtime/patch/core_patch.dart 572:46                generate
packages/graphview/GraphView.dart 296:12                                          <fn>
packages/graphview/GraphView.dart 306:48                                          build
packages/flutter/src/widgets/framework.dart 5583:27                               build
packages/flutter/src/widgets/framework.dart 5471:15                               performRebuild
packages/flutter/src/widgets/framework.dart 5634:11                               performRebuild
packages/flutter/src/widgets/framework.dart 5187:7                                rebuild
packages/flutter/src/widgets/framework.dart 2895:18                               buildScope
packages/flutter/src/widgets/binding.dart 984:9                                   drawFrame
packages/flutter/src/rendering/binding.dart 457:5                                 [_handlePersistentFrameCallback]
packages/flutter/src/scheduler/binding.dart 1325:7                                [_invokeFrameCallback]
packages/flutter/src/scheduler/binding.dart 1255:9                                handleDrawFrame
packages/flutter/src/scheduler/binding.dart 1113:5                                [_handleDrawFrame]
lib/_engine/engine/platform_dispatcher.dart 1274:5                                invoke
lib/_engine/engine/platform_dispatcher.dart 248:5                                 invokeOnDrawFrame
lib/_engine/engine/initialization.dart 186:36                                     <fn>
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 574:37  _checkAndCall
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 579:39  dcall

════════════════════════════════════════════════════════════════════════════════════════════════════
410
Another exception was thrown: RangeError (index): Index out of range: index should be less than 8: 8

[emmby]

Fix: #115