dartdoc failed: NoSuchMethodError: The getter 'element' was called on null

[Dinesh-DK]

When trying to run dartdoc in our library syncfusion_flutter_charts the dartdoc generation task fails with a dartdoc internal error message. Also this doesn't occur with the older versions of dartdoc(other than 0.40.0). I have attached the error log below.

used dartdoc version : 0.40.0

flutter_charts_dartdoc.txt

dartdoc failed: NoSuchMethodError: The getter 'element' was called on null.
Receiver: null
Tried calling: element
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)
#1      new ElementType.from (package:dartdoc/src/element_type.dart:29:11)
#2      new Extension (package:dartdoc/src/model/extension.dart:21:21)
#3      ModelElement._from (package:dartdoc/src/model/model_element.dart:330:14)
#4      new ModelElement.from (package:dartdoc/src/model/model_element.dart:278:40)
#5      Library.extensions.<anonymous closure> (package:dartdoc/src/model/library.dart:202:34)
#6      MappedIterator.moveNext (dart:_internal/iterable.dart:389:20)
#7      new _GrowableList._ofOther (dart:core-patch/growable_array.dart:198:26)
#8      new _List._ofOther (dart:core-patch/array.dart:106:43)
#9      new _List.of (dart:core-patch/array.dart:57:18)
#10     new List.of (dart:core-patch/array_patch.dart:52:20)
#11     Iterable.toList (dart:core/iterable.dart:366:12)
#12     Library.extensions (package:dartdoc/src/model/library.dart:203:10)
#13     Library.modelElementsMap (package:dartdoc/src/model/library.dart:607:17)
#14     Library.allModelElements (package:dartdoc/src/model/library.dart:647:33)
#15     PackageGraph.allModelElements.<anonymous closure>.<anonymous closure> (package:dartdoc/src/model/package_graph.dart:915:48)
#16     SetMixin.forEach (dart:collection/set.dart:142:30)
#17     PackageGraph.allModelElements.<anonymous closure> (package:dartdoc/src/model/package_graph.dart:914:18)
#18     SetMixin.forEach (dart:collection/set.dart:142:30)
#19     PackageGraph.allModelElements (package:dartdoc/src/model/package_graph.dart:908:52)
#20     PackageGraph.precacheLocalDocs.sync_op (package:dartdoc/src/model/package_graph.dart:121:19)
#21     _SyncIterator.moveNext (dart:core-patch/core_patch.dart:181:26)
#22     Future.wait (dart:async/future.dart:393:26)
#23     PackageGraph.initializePackageGraph (package:dartdoc/src/model/package_graph.dart:73:18)
#24     PubPackageBuilder.buildPackageGraph (package:dartdoc/src/model/package_builder.dart:72:20)
<asynchronous suspension>
#25     Dartdoc.generateDocsBase (package:dartdoc/dartdoc.dart:182:20)
<asynchronous suspension>
#26     Dartdoc.generateDocs (package:dartdoc/dartdoc.dart:223:28)
<asynchronous suspension>
#27     Dartdoc.executeGuarded.<anonymous closure> (package:dartdoc/dartdoc.dart:500:9)
<asynchronous suspension>

Program returned code  : 255

[jcollins-g]

I am unable to reproduce this problem locally either with v0.40.0 or the newly released v0.41.0.

Can you please specify the version of Flutter you are using, and confirm that you have run "pub upgrade" if you are using a local checkout of dartdoc?

[jcollins-g]

@Dinesh-DK Will close in a couple days unless I hear back, assuming that it is related to previously closed bugs on this topic. This is the first report of this problem with 0.40.0 however so I'd like to be sure before doing that.

[BrianM-saltus]

I am running into the same issue. Today is the first time I have used dartdoc. I used it on two programs a dart cli program and a flutter program. The cli program worked without issue, however I see the same error as Dinesh-DK when trying to use it with the flutter program.

I even created a fresh flutter app and the error still happened. I am running Flutter 2.0.3. Also i checked i am using 0.41 of dartdoc

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 2.0.3, on Microsoft Windows [Version 10.0.18363.1440], locale en-US)
[√] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
[√] Chrome - develop for the web
[√] Visual Studio - develop for Windows (Visual Studio Community 2019 16.9.2)
[√] Android Studio (version 4.0)
[√] VS Code (version 1.55.0)
[√] Connected device (2 available)

[jcollins-g]

This is very odd, especially since pub.dev seems to be processing flutter packages just fine. Perhaps it has something to do with Windows. Will investigate.

[BrianM-saltus]

Thank you. If you want/need me to try anything please just ask.

[jcollins-g]

Swinging back around to this, I've tried several ways of reproducing this on non-Windows platforms but failed. I am working on getting access to/setting up a Dart development platform on a Windows system to reproduce the problem.

Some questions I have:

• Is this issue being experienced by anyone not on Windows?
• Does flutter analyze return with no errors on your project? That is a prerequisite for dartdoc to function properly. It does return with no errors for me on syncfusion, but again that package works fine for me, not tried on Windows yet.

[wolfenrain]

A member of my team is currently experiencing this problem as well on one of the packages I maintain. Both in the CI/CD (Linux) and locally (Mac).

Using dartdoc v0.39.0. And it only occurs on our newly created web interface package. After reviewing our own code I wasn't able to find anything strange with it as to why it might occur but it might give some insights?

The relevant source can be found here

[nikto-b]

Have reproduced
Linux
dartdoc version: 0.39.0

[✓] Flutter (Channel stable, 2.0.4, on Linux, locale ru_RU.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)

Steps to reproduce:

1. Run Linux
2. flutter create dartdoc_bug_test
3. cd dartdoc_bug_test
4. dartdoc
5. That's it

Documenting dartdoc_bug_test...
\
dartdoc failed: NoSuchMethodError: The getter 'element' was called on null.
Receiver: null
Tried calling: element
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)
#1      new ElementType.from (package:dartdoc/src/element_type.dart:29:11)
#2      new Extension (package:dartdoc/src/model/extension.dart:21:21)
#3      ModelElement._from (package:dartdoc/src/model/model_element.dart:330:14)
#4      new ModelElement.from (package:dartdoc/src/model/model_element.dart:278:40)
#5      Library.extensions.<anonymous closure> (package:dartdoc/src/model/library.dart:202:34)
#6      MappedIterator.moveNext (dart:_internal/iterable.dart:389:20)
#7      new _GrowableList._ofOther (dart:core-patch/growable_array.dart:198:26)
#8      new _List._ofOther (dart:core-patch/array.dart:106:43)
#9      new _List.of (dart:core-patch/array.dart:57:18)
#10     new List.of (dart:core-patch/array_patch.dart:52:20)
#11     Iterable.toList (dart:core/iterable.dart:366:12)
#12     Library.extensions (package:dartdoc/src/model/library.dart:203:10)
#13     Library.modelElementsMap (package:dartdoc/src/model/library.dart:607:17)
#14     Library.allModelElements (package:dartdoc/src/model/library.dart:647:33)
#15     PackageGraph.allModelElements.<anonymous closure>.<anonymous closure> (package:dartdoc/src/model/package_graph.dart:915:48)
#16     SetMixin.forEach (dart:collection/set.dart:142:30)
#17     PackageGraph.allModelElements.<anonymous closure> (package:dartdoc/src/model/package_graph.dart:914:18)
#18     SetMixin.forEach (dart:collection/set.dart:142:30)
#19     PackageGraph.allModelElements (package:dartdoc/src/model/package_graph.dart:908:52)
#20     PackageGraph.precacheLocalDocs.sync_op (package:dartdoc/src/model/package_graph.dart:121:19)
#21     _SyncIterator.moveNext (dart:core-patch/core_patch.dart:181:26)
#22     Future.wait (dart:async/future.dart:393:26)
#23     PackageGraph.initializePackageGraph (package:dartdoc/src/model/package_graph.dart:73:18)
#24     PubPackageBuilder.buildPackageGraph (package:dartdoc/src/model/package_builder.dart:72:20)
<asynchronous suspension>
#25     Dartdoc.generateDocsBase (package:dartdoc/dartdoc.dart:182:20)
<asynchronous suspension>
#26     Dartdoc.generateDocs (package:dartdoc/dartdoc.dart:223:28)
<asynchronous suspension>
#27     Dartdoc.executeGuarded.<anonymous closure> (package:dartdoc/dartdoc.dart:500:9)
<asynchronous suspension>

[nikto-b]

Fixed by updating to dartdoc version: 0.40.0

[jcollins-g]

I can not reproduce this problem on 0.40.0 or higher, but can reliably reproduce it on 0.39.0 -- this is a known bug with that version. For anyone reporting this issue, have you checked that your PATH is correct and pointing to a dartdoc that reports greater than 0.39.0?

I am going to add some debugging output on exceptions so that it is clear which version is being executed for future crashes -- it's particularly confusing since people can use pub global activate dartdoc as well as the dartdoc from either a Dart SDK or Flutter SDK installation.

[sjimbonator]

I am the team member @wolfenrain mentioned. We are still having this problem on dartdoc version 0.42.0 but only on one specific package.