characterLocation of Enum implicit accessors is invalid

[jcollins-g]

This throws an assert if accessed:

build-angular->=5.1.0:   warning: unresolved doc reference [TemplateRef `templateRef`], from angular.ViewContainerRef.createEmbeddedView: (file:///tmp/angularUPLJQI/lib/src/core/linker/view_container_ref.dart:53:19)
build-angular->=5.1.0:   warning: unresolved doc reference [TemplateRef `templateRef`], from angular.ViewContainerRef.insertEmbeddedView: (file:///tmp/angularUPLJQI/lib/src/core/linker/view_container_ref.dart:49:19)
build-angular->=5.1.0:
build-angular->=5.1.0: dartdoc 0.44.0 (/home/runner/work/dartdoc/dartdoc/bin/dartdoc.dart) failed: 'package:dartdoc/src/model/model_element.dart': Failed assertion: line 790 pos 14: 'element.nameOffset >= 0': Invalid location data for element: angular.ViewEncapsulation.Emulated
build-angular->=5.1.0: #0      _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:46:39)
build-angular->=5.1.0: #1      _AssertionError._throwNew (dart:core-patch/errors_patch.dart:36:5)
build-angular->=5.1.0: #2      ModelElement.characterLocation (package:dartdoc/src/model/model_element.dart:790:14)
build-angular->=5.1.0: #3      ModelElement.location (package:dartdoc/src/model/model_element.dart:739:9)
build-angular->=5.1.0: #4      PackageGraph._warnOnElement (package:dartdoc/src/model/package_graph.dart:489:69)
build-angular->=5.1.0: #5      PackageGraph.warnOnElement (package:dartdoc/src/model/package_graph.dart:311:5)
build-angular->=5.1.0: #6      Warnable.warn (package:dartdoc/src/warnings.dart:302:18)
build-angular->=5.1.0: #7      _makeLinkNode (package:dartdoc/src/markdown_processor.dart:968:16)
build-angular->=5.1.0: #8      new MarkdownDocument.withElementLinkResolver.linkResolver (package:dartdoc/src/markdown_processor.dart:1091:14)
build-angular->=5.1.0: #9      LinkSyntax._resolveReferenceLink (package:markdown/src/inline_parser.dart:1057:34)
build-angular->=5.1.0: #10     LinkSyntax._tryCreateReferenceLink (package:markdown/src/inline_parser.dart:1085:12)
build-angular->=5.1.0: #11     LinkSyntax.close (package:markdown/src/inline_parser.dart:1028:12)
build-angular->=5.1.0: #12     InlineParser._linkOrImage (package:markdown/src/inline_parser.dart:152:29)
build-angular->=5.1.0: #13     InlineParser.parse (package:markdown/src/inline_parser.dart:108:9)
build-angular->=5.1.0: #14     MarkdownDocument._parseInlineContent (package:dartdoc/src/markdown_processor.dart:1140:67)
build-angular->=5.1.0: #15     MarkdownDocument._parseInlineContent (package:dartdoc/src/markdown_processor.dart:1145:9)
build-angular->=5.1.0: #16     MarkdownDocument.parseMarkdownText (package:dartdoc/src/markdown_processor.dart:1130:5)
build-angular->=5.1.0: #17     Documentation._parseDocumentation (package:dartdoc/src/model/documentation.dart:73:21)
build-angular->=5.1.0: #18     Documentation._renderDocumentation (package:dartdoc/src/model/documentation.dart:48:23)
build-angular->=5.1.0: #19     Documentation.asHtml (package:dartdoc/src/model/documentation.dart:30:7)
build-angular->=5.1.0: #20     ModelElement.documentationAsHtml (package:dartdoc/src/model/model_element.dart:727:62)
build-angular->=5.1.0: #21     EnumField.oneLineDoc (package:dartdoc/src/model/enum.dart:88:28)
build-angular->=5.1.0: #22     _Renderer_GetterSetterCombo.propertyMap.<anonymous closure>.<anonymous closure> (package:dartdoc/src/generator/templates.runtime_renderers.dart:6460:42)
build-angular->=5.1.0: #23     _Renderer_GetterSetterCombo.propertyMap.<anonymous closure>.<anonymous closure> (package:dartdoc/src/generator/templates.runtime_renderers.dart:6464:43)
build-angular->=5.1.0: #24     RendererBase.getFields (package:dartdoc/src/mustachio/renderer_base.dart:179:39)
build-angular->=5.1.0: #25     RendererBase.renderBlock (package:dartdoc/src/mustachio/renderer_base.dart:204:23)
build-angular->=5.1.0: #26     RendererBase.partial (package:dartdoc/src/mustachio/renderer_base.dart:265:5)
build-angular->=5.1.0: #27     RendererBase.renderBlock (package:dartdoc/src/mustachio/renderer_base.dart:209:9)
build-angular->=5.1.0: #28     _render_Field (package:dartdoc/src/generator/templates.runtime_renderers.dart:5539:12)
build-angular->=5.1.0: #29     _Renderer_Container.propertyMap.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:dartdoc/src/generator/templates.runtime_renderers.dart:3509:32)
build-angular->=5.1.0: #30     MappedListIterable.elementAt (dart:_internal/iterable.dart:413:31)
build-angular->=5.1.0: #31     ListIterator.moveNext (dart:_internal/iterable.dart:342:26)
build-angular->=5.1.0: #32     StringBuffer.writeAll (dart:core-patch/string_buffer_patch.dart:96:19)
build-angular->=5.1.0: #33     RendererBase.section (package:dartdoc/src/mustachio/renderer_base.dart:242:38)
build-angular->=5.1.0: #34     RendererBase.renderBlock (package:dartdoc/src/mustachio/renderer_base.dart:207:9)
build-angular->=5.1.0: #35     RendererBase.section (package:dartdoc/src/mustachio/renderer_base.dart:230:9)
build-angular->=5.1.0: #36     RendererBase.renderBlock (package:dartdoc/src/mustachio/renderer_base.dart:207:9)
build-angular->=5.1.0: #37     _render_Enum (package:dartdoc/src/generator/templates.runtime_renderers.dart:4643:12)
build-angular->=5.1.0: #38     _Renderer_EnumTemplateData.propertyMap.<anonymous closure>.<anonymous closure> (package:dartdoc/src/generator/templates.runtime_renderers.dart:4724:28)
build-angular->=5.1.0: #39     RendererBase.section (package:dartdoc/src/mustachio/renderer_base.dart:255:33)
build-angular->=5.1.0: #40     RendererBase.renderBlock (package:dartdoc/src/mustachio/renderer_base.dart:207:9)
build-angular->=5.1.0: #41     _render_EnumTemplateData (package:dartdoc/src/generator/templates.runtime_renderers.dart:4696:12)
build-angular->=5.1.0: #42     renderEnum (package:dartdoc/src/generator/templates.runtime_renderers.dart:4689:10)
build-angular->=5.1.0: #43     DartdocGeneratorBackend.generateEnum (package:dartdoc/src/generator/dartdoc_generator_backend.dart:199:19)
build-angular->=5.1.0: #44     GeneratorFrontEnd._generateDocs (package:dartdoc/src/generator/generator_frontend.dart:229:29)
build-angular->=5.1.0: #45     GeneratorFrontEnd.generate (package:dartdoc/src/generator/generator_frontend.dart:21:5)
build-angular->=5.1.0: #46     Dartdoc.generateDocsBase (package:dartdoc/dartdoc.dart:207:23)
build-angular->=5.1.0: <asynchronous suspension>
build-angular->=5.1.0: #47     Dartdoc.generateDocs (package:dartdoc/dartdoc.dart:239:28)
build-angular->=5.1.0: <asynchronous suspension>
build-angular->=5.1.0: #48     Dartdoc.executeGuarded.<anonymous closure> (package:dartdoc/dartdoc.dart:503:9)
build-angular->=5.1.0: <asynchronous suspension>
build-angular->=5.1.0:

ProcessException: SubprocessLauncher got non-zero exitCode: 255

The most common cause of this is a warning triggering on an implicit accessor.