dartdoc can't run successfully on pub #3196
Description
So, I'm publishing this package on pub.dev, and when I look at the score breakdown, I get a bunch of errors. In the "Health suggestions" section, it says to run dartfmt on every file in the lib folder. In the "Maintenance issues and suggestions" section, it says "Make sure dartdoc successfully runs on your package's source files. (-10 points)" and spits out this error:
exitCode: 255 stdout: parsing /tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/expose.dart... parsing /tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/plexus.dart... parsing /dart-sdk/lib/core/core.dart... parsing /dart-sdk/lib/collection/collection.dart... parsing /dart-sdk/lib/internal/internal.dart... parsing /dart-sdk/lib/async/async.dart... parsing /dart-sdk/lib/convert/convert.dart... parsing /dart-sdk/lib/typed_data/typed_data.dart... parsing /dart-sdk/lib/math/math.dart... parsing /tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/src/expose/list.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/meta-1.1.8/lib/meta.dart... parsing /tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/src/expose/maps.dart... parsing /tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/src/ansi.dart... parsing /dart-sdk/lib/io/io.dart... parsing /dart-sdk/lib/developer/developer.dart... parsing /dart-sdk/lib/isolate/isolate.dart... parsing /dart-sdk/lib/_http/http.dart... parsing /tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/src/event.dart... parsing /tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/src/extension/iterable.dart... parsing /tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/src/extension/string.dart... [...] parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/instrumentation/file_instrumentation.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/task/model.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/args-1.5.2/lib/command_runner.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/http-0.12.0+2/lib/src/browser_client.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/http-0.12.0+2/lib/src/io_client.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/http-0.12.0+2/lib/src/mock_client.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/package_config-1.1.0/lib/src/packages_io_impl.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/src/dart/analysis/analysis_context_collection.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/src/dart/analysis/context_builder.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/src/source/package_map_provider.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/src/generated/sdk_io.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/src/source/sdk_ext.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/src/source/custom_resolver.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/src/source/path_filter.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/analyzer-0.39.2+1/lib/src/util/glob.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/args-1.5.2/lib/src/help_command.dart... parsing /tmp/pub-cache-dirTBJCBR/hosted/pub.dartlang.org/args-1.5.2/lib/src/usage_exception.dart... Initialized dartdoc with 879 libraries in 89.7 seconds documenting plexus Generating docs for library expose from package:plexus/expose.dart... stderr: Documenting plexus... warning: expose has no library level documentation comments, from expose: (file:///tmp/pub-dartlang-dartdocWRUKEU/pkg/lib/expose.dart:1:9) Unhandled exception: type 'FunctionTypeImpl' is not a subtype of type 'InterfaceType' #0 DefinedElementType.interfaceType (package:dartdoc/src/element_type.dart:324:38) #1 DefinedElementType.instantiatedType (package:dartdoc/src/element_type.dart:331:12) #2 Extension._couldApplyTo (package:dartdoc/src/model.dart:1350:47) #3 Extension.couldApplyTo (package:dartdoc/src/model.dart:1346:33) #4 Class.potentiallyApplicableExtensions.
I'm really confused as to what I might be doing wrong and would love some help.