fix a Scrollbar example crash

[xu-baolin]

Fix a scrollbar example crash.
https://api.flutter.dev/flutter/material/Scrollbar-class.html#material.Scrollbar.1

[flutter-dashboard]

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[TahaTesser]

Hi @xu-baolin
I cannot reproduce any crash using the sample https://api.flutter.dev/flutter/material/Scrollbar-class.html#material.Scrollbar.2, on the latest stable or previous stable or master.

[xu-baolin]

Did you have tried to move the scrollbar thumb?

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________________________________ 发件人: Taha Tesser ***@***.***> 发送时间: 2023年06月29日 21:06 收件人: flutter/flutter ***@***.***> 抄送: 徐宝林(Ava) ***@***.***>; Mention ***@***.***> 主题: Re: [flutter/flutter] fix a Scrollbar example crash (PR #127925) Hi @xu-baolin<https://github.com/xu-baolin> I cannot reproduce any crash using the sample https://api.flutter.dev/flutter/material/Scrollbar-class.html#material.Scrollbar.2, on the latest stable or previous stable or master. ― Reply to this email directly, view it on GitHub<#127925 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AOR66GBHBPEJYA7TVGRGQFDXNV4WHANCNFSM6AAAAAAYVCCTDE>. You are receiving this because you were mentioned.Message ID: ***@***.***>

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[TahaTesser]

https://api.flutter.dev/flutter/material/Scrollbar-class.html#material.Scrollbar.2

Yes, tried all channels on Dartpad again to be sure.

[xu-baolin]

Sorry, the reference link maybe wrong but the sample I fixed is still crashing on api.flutter.dev

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________________________________ 发件人: Taha Tesser ***@***.***> 发送时间: 2023年06月29日 22:01 收件人: flutter/flutter ***@***.***> 抄送: 徐宝林(Ava) ***@***.***>; Mention ***@***.***> 主题: Re: [flutter/flutter] fix a Scrollbar example crash (PR #127925) https://api.flutter.dev/flutter/material/Scrollbar-class.html#material.Scrollbar.2 Yes, tried all channels on Dartpad again to be sure. ― Reply to this email directly, view it on GitHub<#127925 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AOR66GH2JKEQ5C7FICURKWLXNWDEPANCNFSM6AAAAAAYVCCTDE>. You are receiving this because you were mentioned.Message ID: ***@***.***>

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[TahaTesser]

Ah yes, its actually https://api.flutter.dev/flutter/material/Scrollbar-class.html#material.Scrollbar.1

[TahaTesser]

Is it a good practice to add primary: true?

[xu-baolin]

Yeah, I think so. It's easier than specifying a controller explicitly, isn't it?

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________________________________ 来自TT移动邮箱 / From TT mailbox

________________________________ 发件人: Taha Tesser ***@***.***> 发送时间: 2023年06月29日 23:01 收件人: flutter/flutter ***@***.***> 抄送: 徐宝林(Ava) ***@***.***>; Mention ***@***.***> 主题: Re: [flutter/flutter] fix a Scrollbar example crash (PR #127925) Is it a good practice to add primary: true? ― Reply to this email directly, view it on GitHub<#127925 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AOR66GDE3QWBWEWAKR6NSMTXNWKGHANCNFSM6AAAAAAYVCCTDE>. You are receiving this because you were mentioned.Message ID: ***@***.***>

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[TahaTesser]

LGTM

[TahaTesser]

Actually, this will need a test exemption from Hixie to land.
However given this is causing crashes, it would be better to add example test that check if takeException is null.

[TahaTesser]

@Piinks
Is primary: true necessary for cases like this one? #127925 (comment)

[Piinks]

Is primary: true necessary for cases like this one?

@TahaTesser on desktop, yup. Since the api docs are often viewed on the web on desktop, this change makes sense to me. Thanks @xu-baolin!

[Hixie]

@xu-baolin Is writing a test for this on your radar?

[TahaTesser]

LGTM

[TahaTesser]

@xu-baolin
BTW You'll need to remove the missing test class string from sdk/dev/bots/check_code_samples.dart to land this.

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