Restore error message explaining the need to call WidgetsFlutterBinding.ensureInitialized() #78028

lukepighetti · 2021-03-12T14:34:46Z

When using shared_preferences: ^2.0.4, when calling SharedPreferences.getInstance() I get a null check exception.

Fails on

macOS
iOS
Android

Succeeds on

Web

Flutter version & devices

Flutter 2.1.0-10.0.pre • channel dev • https://github.com/flutter/flutter.git
Framework • revision cc9b78fc5c (2 weeks ago) • 2021-02-25 13:26:03 -0800
Engine • revision a252ec09b7
Tools • Dart 2.13.0 (build 2.13.0-77.0.dev)

SM S102DL (mobile)     • RF8N737S2CR                              • android-arm    • Android 10 (API 29)
Luke's iPhone (mobile) • 0bc0c4864d8e08aac4456893cded68bf0b6767d5 • ios            • iOS 14.4
macOS (desktop)        • macos                                    • darwin-x64     • macOS 11.2.1 20D74 darwin-x64
Chrome (web)           • chrome                                   • web-javascript • Google Chrome 89.0.4389.82

MCVE

name: shared_preferences_macos_issue
description: A new Flutter project.
publish_to: "none"
version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter

  cupertino_icons: ^1.0.2
  shared_preferences: ^2.0.4

dev_dependencies:
  flutter_test:
    sdk: flutter

flutter:
  uses-material-design: true

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() async {
  final prefs = await SharedPreferences.getInstance();

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        body: Center(
          child: Text('shared_preferences error'),
        ),
      ),
    );
  }
}

[ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: Null check operator used on a null value
#0      MethodChannel.binaryMessenger
package:flutter/…/services/platform_channel.dart:142
#1      MethodChannel._invokeMethod
package:flutter/…/services/platform_channel.dart:148
#2      MethodChannel.invokeMethod
package:flutter/…/services/platform_channel.dart:331
#3      MethodChannel.invokeMapMethod
package:flutter/…/services/platform_channel.dart:358
#4      MethodChannelSharedPreferencesStore.getAll
package:shared_preferences_platform_interface/method_channel_shared_preferences.dart:44
#5      SharedPreferences._getSharedPreferencesMap
package:shared_preferences/shared_preferences.dart:181
#6      SharedPreferences.getInstance
package:shared_preferences/shared_preferences.dart:57
#7      main
package:shared_preferences_macos_issue/main.dart:5
#8      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:146:25)
#9      _rootRun (dart:async/zone.dart:1354:13)
#10     _CustomZone.run (dart:async/zone.dart:1258:19)
#11     _runZoned (dart:async/zone.dart:1789:10)
#12     runZonedGuarded (dart:async/zone.dart:1777:12)
#13     _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:139:5)
#14     _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:283:19)
#15     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)

The text was updated successfully, but these errors were encountered:

SirusCodes · 2021-03-12T15:07:16Z

Can you run SharedPreferences.getInstance() Before runApp()?

TahaTesser · 2021-03-12T15:18:08Z

Hi @lukepighetti
Thanks for all the information to reproduce the issue.

When running your code sample on the stable and beta channels, we can see the following message to add WidgetsFlutterBinding.ensureInitialized(); and adding the line in the main function before final prefs = await SharedPreferences.getInstance(); line fixes the null check exception error and app launches.

logs

[ +213 ms] Connecting to service protocol: http://127.0.0.1:62225/MZ5j6RDbyEE=/
[ +242 ms] Launching a Dart Developer Service (DDS) instance at http://127.0.0.1:0, connecting to VM service at
http://127.0.0.1:62225/MZ5j6RDbyEE=/.
[ +130 ms] DDS is listening at http://127.0.0.1:62233/df3nJKVqXD4=/.
[  +69 ms] [VERBOSE-2:ui_dart_state.cc(186)] Unhandled Exception: ServicesBinding.defaultBinaryMessenger was accessed before
the binding was initialized.
           If you're running an application and need to access the binary messenger before `runApp()` has been called (for
example, during plugin initialization), then you need to explicitly call the `WidgetsFlutterBinding.ensureInitialized()`
first.
           If you're running a test, you can call the `TestWidgetsFlutterBinding.ensureInitialized()` as the first line in
your test's `main()` method to initialize the binding.
           #0      defaultBinaryMessenger.<anonymous closure> (package:flutter/src/services/binary_messenger.dart:97:7)
           #1      defaultBinaryMessenger (package:flutter/src/services/binary_messenger.dart:110:4)
           #2      MethodChannel.binaryMessenger (package:flutter/src/services/platform_channel.dart:142:62)
           #3      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:148:36)
           #4      MethodChannel.invokeMethod (package:flutter/src/services/platfor<…>
[  +41 ms] Successfully connected to service protocol: http://127.0.0.1:62225/MZ5j6RDbyEE=/
[+1604 ms] DevFS: Creating new filesystem on the device (null)
[  +20 ms] DevFS: Created new filesystem on the device
(file:///Users/tahatesser/Library/Developer/CoreSimulator/Devices/BD94A45F-A994-4FC3-BAD9-448D8D2E0F1B/data/Containers/Data/Ap
plication/ED2609BF-51B0-4EF4-BD19-074669020D42/tmp/stable_flutter9BnASB/stable_flutter/)
[   +9 ms] Updating assets
[ +168 ms] Syncing files to device iPhone 12...

However on the dev and master channels, instead of the above message, we get Unhandled Exception: Null check operator used on a null value but adding WidgetsFlutterBinding.ensureInitialized(); also fixes the issue, and the app launches.

logs

[ +215 ms] Launching a Dart Developer Service (DDS) instance at http://127.0.0.1:0, connecting to VM service at
http://127.0.0.1:61914/nvKr2mRoZAY=/.
[ +169 ms] DDS is listening at http://127.0.0.1:61920/3Ju2HOPbk8o=/.
[  +84 ms] [VERBOSE-2:ui_dart_state.cc(186)] Unhandled Exception: Null check operator used on a null value
           #0      MethodChannel.binaryMessenger (package:flutter/src/services/platform_channel.dart:142:86)
           #1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:148:36)
           #2      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:331:12)
           #3      MethodChannel.invokeMapMethod (package:flutter/src/services/platform_channel.dart:358:49)
           #4      MethodChannelSharedPreferencesStore.getAll
(package:shared_preferences_platform_interface/method_channel_shared_preferences.dart:44:25)
           #5      SharedPreferences._getSharedPreferencesMap (package:shared_preferences/shared_preferences.dart:181:57)
           #6      SharedPreferences.getInstance (package:shared_preferences/shared_preferences.dart:57:19)
           #7      main (package:triage/main.dart:5:41)
           #8      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:146:25)
           #9      _rootRun (dart:async/zone.dart:1354:1<…>
[  +40 ms] Successfully connected to service protocol: http://127.0.0.1:61914/nvKr2mRoZAY=/
[ +100 ms] DevFS: Creating new filesystem on the device (null)
[  +31 ms] DevFS: Created new filesystem on the device
(file:///Users/tahatesser/Library/Developer/CoreSimulator/Devices/BD94A45F-A994-4FC3-BAD9-448D8D2E0F1B/data/Containers/Data/Ap
plication/EAD05D9E-EAFA-441E-84A6-102FE2F98379/tmp/dev_flutterePbWK0/dev_flutter/)
[   +6 ms] Updating assets
[ +195 ms] Syncing files to device iPhone 12...

code sample

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  final prefs = await SharedPreferences.getInstance();

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        body: Center(
          child: Text('shared_preferences error'),
        ),
      ),
    );
  }
}

flutter doctor -v

[✓] Flutter (Channel stable, 2.0.1, on macOS 11.2.3 20D91 darwin-x64, locale en-GB)
    • Flutter version 2.0.1 at /Users/tahatesser/Code/flutter_stable
    • Framework revision c5a4b4029c (8 days ago), 2021-03-04 09:47:48 -0800
    • Engine revision 40441def69
    • Dart version 2.12.0

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Volumes/Extreme/SDK
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Volumes/Extreme/SDK
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Volumes/Extreme/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.54.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (3 available)
    • iPhone 12 (mobile) • BD94A45F-A994-4FC3-BAD9-448D8D2E0F1B • ios            •
      com.apple.CoreSimulator.SimRuntime.iOS-14-4 (simulator)
    • macOS (desktop)    • macos                                • darwin-x64     • macOS
      11.2.3 20D91 darwin-x64
    • Chrome (web)       • chrome                               • web-javascript • Google
      Chrome 89.0.4389.82

• No issues found!

[✓] Flutter (Channel beta, 2.0.1, on macOS 11.2.3 20D91 darwin-x64, locale en-GB)
    • Flutter version 2.0.1 at /Users/tahatesser/Code/flutter_beta
    • Framework revision c5a4b4029c (8 days ago), 2021-03-04 09:47:48 -0800
    • Engine revision 40441def69
    • Dart version 2.12.0

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Volumes/Extreme/SDK
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Volumes/Extreme/SDK
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Volumes/Extreme/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.54.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (3 available)
    • iPhone 12 (mobile) • BD94A45F-A994-4FC3-BAD9-448D8D2E0F1B • ios            •
      com.apple.CoreSimulator.SimRuntime.iOS-14-4 (simulator)
    • macOS (desktop)    • macos                                • darwin-x64     • macOS
      11.2.3 20D91 darwin-x64
    • Chrome (web)       • chrome                               • web-javascript • Google
      Chrome 89.0.4389.82

• No issues found!

[✓] Flutter (Channel dev, 2.1.0-10.0.pre, on macOS 11.2.3 20D91 darwin-x64, locale en-GB)
    • Flutter version 2.1.0-10.0.pre at /Users/tahatesser/Code/flutter_dev
    • Framework revision cc9b78fc5c (2 weeks ago), 2021-02-25 13:26:03 -0800
    • Engine revision a252ec09b7
    • Dart version 2.13.0 (build 2.13.0-77.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Volumes/Extreme/SDK
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Volumes/Extreme/SDK
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Volumes/Extreme/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.54.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (3 available)
    • iPhone 12 (mobile) • BD94A45F-A994-4FC3-BAD9-448D8D2E0F1B • ios            •
      com.apple.CoreSimulator.SimRuntime.iOS-14-4 (simulator)
    • macOS (desktop)    • macos                                • darwin-x64     • macOS
      11.2.3 20D91 darwin-x64
    • Chrome (web)       • chrome                               • web-javascript • Google
      Chrome 89.0.4389.82

• No issues found!

[✓] Flutter (Channel master, 2.1.0-11.0.pre.229, on macOS 11.2.3 20D91 darwin-x64, locale
    en-GB)
    • Flutter version 2.1.0-11.0.pre.229 at /Users/tahatesser/Code/flutter_master
    • Framework revision d20ec4c7d8 (9 hours ago), 2021-03-11 22:18:51 -0800
    • Engine revision 1b68503bc8
    • Dart version 2.13.0 (build 2.13.0-125.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Volumes/Extreme/SDK
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Volumes/Extreme/SDK
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Volumes/Extreme/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.54.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (4 available)
    • Redmi K20 Pro (mobile) • def0ad20                             • android-arm64  •
      Android 10 (API 29)
    • iPhone 12 (mobile)     • BD94A45F-A994-4FC3-BAD9-448D8D2E0F1B • ios            •
      com.apple.CoreSimulator.SimRuntime.iOS-14-4 (simulator)
    • macOS (desktop)        • macos                                • darwin-x64     •
      macOS 11.2.3 20D91 darwin-x64
    • Chrome (web)           • chrome                               • web-javascript •
      Google Chrome 89.0.4389.82

• No issues found!

Thank you for filing the issue!

lukepighetti · 2021-03-12T15:32:32Z

I almost feel comfortable closing this issue now that it's documented. I'll leave it up to you. Thanks for the fast triage.

stuartmorgan-g · 2021-03-18T18:26:23Z

@Piinks It looks like the deprecated codepath you removed (#73750) had a very useful warning, but the new codepath doesn't. Can we get this added to the new codepath as well?

(/cc @Hixie since it's about actionable error messages in core framework code.)

Piinks · 2021-03-18T19:19:47Z

@Piinks It looks like the deprecated codepath you removed (#73750) had a very useful warning, but the new codepath doesn't. Can we get this added to the new codepath as well?

Most definitely! Apologies, I did not realize we were losing that error message in the process.

Hixie · 2021-03-20T00:10:57Z

I'm already working on that.

stuartmorgan-g · 2021-11-21T17:28:03Z

@Hixie Is restoring this error message still something that's in progress?

Jordan-Nelson · 2022-01-26T16:25:18Z

@Hixie @stuartmorgan It looks like this is already in progress, but if it is not, I am happy to take a shot at it. Putting the assertion back in place seems simple enough. It looks like you are planning to resolve this as part of a much larger change though.

Edit: It looks like a basic error message was already added back in master at least for MethodChannel in #92758. Looks like the in progress PR adds some more context and possibly some utils for checking that the bindings have been initialized. I'll wait for that 👍

Hixie · 2022-01-26T23:47:56Z

Yeah a comprehensive fix is in #89451. It's taking a long time to land because it requires an intense number of changes to Google's codebase (Google has contributed all its code as tests, which is fantastic in terms of catching regressions, but makes life non-trivial when changing a core API...). (For non-Google codebases, dart fix will be enough to migrate a codebase, but unfortunately that tool doesn't work in Google's specific setup yet.)

github-actions · 2022-02-17T23:00:43Z

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

TahaTesser added the in triage Presently being triaged by the triage team label Mar 12, 2021

lukepighetti changed the title ~~shared_preferences: Null check operator used on a null value thrown on getInstance()~~ shared_preferences: null check exception thrown on getInstance() Mar 12, 2021

stuartmorgan-g added framework flutter/packages/flutter repository. See also f: labels. P2 Important issues not at the top of the work list and removed p: first party p: shared_preferences Plugin to read and write Shared Preferences labels Mar 18, 2021

TahaTesser mentioned this issue Mar 22, 2021

Asset names cannot contain umlauts #78725

Closed

stuartmorgan-g mentioned this issue Apr 20, 2021

Document WidgetsFlutterBinding.ensureInitialized for early plugin calls #77745

Closed

stuartmorgan-g changed the title ~~shared_preferences: null check exception thrown on getInstance()~~ Restore error message explaining the need to call WidgetsFlutterBinding.ensureInitialized() Apr 20, 2021

This was referenced May 20, 2021

NPE when get instance in main function #83011

Closed

NullError when calling MethodChannel.invokeListMethod #80956

Closed

stuartmorgan-g mentioned this issue May 31, 2021

shared_preferences doesn't work in ios simulator #83656

Closed

stuartmorgan-g mentioned this issue Jun 10, 2021

[path_provider] Error handle for WidgetsFlutterBinding added flutter/plugins#4032

Closed

11 tasks

stuartmorgan-g mentioned this issue Aug 17, 2021

local_auth: _CastError (Null check operator used on a null value) #88350

Closed

apstanisic mentioned this issue Aug 28, 2021

Cannot use on flutter 2.2.3 and MacOS apstanisic/directus-dart#19

Closed

stuartmorgan-g mentioned this issue Nov 21, 2021

Shared Preferences fails to initialize. #93999

Closed

stuartmorgan-g mentioned this issue Dec 10, 2021

SharedPreferences crash on startup application created with flutter 2.8 #95031

Closed

ookami-kb mentioned this issue Dec 13, 2021

path_provider package always show Null check operator error #95155

Closed

nt4f04uNd mentioned this issue Dec 26, 2021

Clean up the bindings APIs. #89451

Merged

8 tasks

Jordan-Nelson mentioned this issue Jan 26, 2022

Provide better error message when Amplify.addPlugin is called before runApp() aws-amplify/amplify-flutter#1309

Closed

fluttergithubbot closed this as completed in #89451 Feb 3, 2022

github-actions bot locked as resolved and limited conversation to collaborators Feb 17, 2022

flutter-triage-bot bot added the package flutter/packages repository. See also p: labels. label Jul 5, 2023

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Restore error message explaining the need to call WidgetsFlutterBinding.ensureInitialized() #78028

Restore error message explaining the need to call WidgetsFlutterBinding.ensureInitialized() #78028

lukepighetti commented Mar 12, 2021 •

edited

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SirusCodes commented Mar 12, 2021

TahaTesser commented Mar 12, 2021

lukepighetti commented Mar 12, 2021

stuartmorgan-g commented Mar 18, 2021

Piinks commented Mar 18, 2021

Hixie commented Mar 20, 2021

stuartmorgan-g commented Nov 21, 2021

Jordan-Nelson commented Jan 26, 2022 •

edited

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Hixie commented Jan 26, 2022

github-actions bot commented Feb 17, 2022

Restore error message explaining the need to call WidgetsFlutterBinding.ensureInitialized() #78028

Restore error message explaining the need to call WidgetsFlutterBinding.ensureInitialized() #78028

Comments

lukepighetti commented Mar 12, 2021 • edited Loading

Flutter version & devices

MCVE

SirusCodes commented Mar 12, 2021

TahaTesser commented Mar 12, 2021

lukepighetti commented Mar 12, 2021

stuartmorgan-g commented Mar 18, 2021

Piinks commented Mar 18, 2021

Hixie commented Mar 20, 2021

stuartmorgan-g commented Nov 21, 2021

Jordan-Nelson commented Jan 26, 2022 • edited Loading

Hixie commented Jan 26, 2022

github-actions bot commented Feb 17, 2022

lukepighetti commented Mar 12, 2021 •

edited

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Jordan-Nelson commented Jan 26, 2022 •

edited

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