Build is crashing with unhandled exception after upgrade to `build_runner 2.4.4`

[elliette]

Building the Dart debug extension is crashing with the following unhandled exception with build_runner 2.4.4 (does not crash with build_runner 2.4.3):

Invalid argument(s): Required input cycle for [{autoApply: AutoApply.none, import: tool/copy_builder.dart, builderFactories: [copyBuilder], buildExtensions: {web/{{}}.dart.js: [compiled/{{}}.dart.js], web/static_assets/{{}}.png: [compiled/static_assets/{{}}.png], web/static_assets/{{}}.html: [compiled/static_assets/{{}}.html], web/static_assets/{{}}.css: [compiled/static_assets/{{}}.css], web/manifest.json: [compiled/manifest.json]}, requiredInputs: [.js, .png, .html, .css, .json], runsBefore: [], isOptional: false, buildTo: BuildTo.source, defaults: Instance of 'TargetBuilderConfigDefaults'}]

I see that error was added here:

• Use topologicalSort with a secondary sort #3507

Note that required_inputs to the extension's build.yaml was added in dart-lang/webdev#2117

[natebosch]

I think that the difference is probably a change in the reaction to a cycle of size 1.