fix(flutter): Guard script completion by buenaflor · Pull Request #3912 · getsentry/sentry-dart

buenaflor · 2026-07-21T09:04:03Z

📜 Description

The Flutter web script loader now settles its load future at most once and cancels both DOM event subscriptions afterward. Browser regression tests cover both load-then-error and error-then-load delivery.

💡 Motivation and Context

Browsers can deliver more than one terminal event for the same script element. The second event previously completed the same Completer again, surfacing StateError: Bad state: Future already completed as an SDK-originated fatal event. Keeping the subscriptions active after settlement also retained their callbacks and captured state for the lifetime of the script element.

Closes #3906

💚 How did you test it?

Temporarily restored the original implementation and ran the browser suite. Both regression tests failed with Bad state: Future already completed; with the fix restored, all browser tests passed.

📝 Checklist

I reviewed submitted code
I added tests to verify changes
No new PII added or SDK only sends newly added PII if sendDefaultPii is enabled
I updated the docs if needed
All tests passing
Public API changes reviewed by another Mobile SDK team member or implemented according to the develop docs spec
No breaking changes

Ignore repeated load and error events after the web script loader. Prevent SDK-originated StateError events when browsers redeliver terminal script events. Fixes #3906 Co-Authored-By: Codex <[email protected]>

github-actions · 2026-07-21T09:04:23Z

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).

Features

(replay) Record segment names on Android by buenaflor in #3897
(tracing) Emit segment name source by buenaflor in #3904

Fixes

Flutter

Guard script completion by buenaflor in #3912

Add app start screen attribute by buenaflor in #3893
Prevent StateError when delayed frames list is empty by muhammadkamel in #3876

Other

(metrics) Add missing metric byte outcomes by buenaflor in #3905

Dependencies

Deps

chore(deps): update Native SDK to v0.15.4 by github-actions in #3910
chore(deps): update Android SDK to v8.49.0 by github-actions in #3895
chore(deps): update Native SDK to v0.15.3 by github-actions in #3862
chore(deps): update Cocoa SDK to v8.58.4 by github-actions in #3864
chore(deps): update Android SDK to v8.48.0 by github-actions in #3873

Internal Changes

(dart) Accept beta wasm function name by sentry-junior in #3898

_{🤖 This preview updates automatically when you update the PR.}

codecov · 2026-07-21T09:06:12Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.90%. Comparing base (a28f929) to head (ab59bbb).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3912      +/-   ##
==========================================
+ Coverage   87.56%   91.90%   +4.33%     
==========================================
  Files         338      105     -233     
  Lines       12345     3828    -8517     
==========================================
- Hits        10810     3518    -7292     
+ Misses       1535      310    -1225

Flag	Coverage Δ
sentry	`?`
sentry_dio	`?`
sentry_drift	`?`
sentry_file	`?`
sentry_firebase_remote_config	`100.00% <ø> (ø)`
sentry_flutter	`91.52% <ø> (ø)`
sentry_grpc	`?`
sentry_hive	`?`
sentry_isar	`?`
sentry_link	`?`
sentry_logging	`?`
sentry_sqflite	`?`
sentry_supabase	`97.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

Copilot

Pull request overview

This PR fixes a Flutter Web regression where a <script> element can emit more than one terminal event (load/error), previously causing Completer double-completion and surfacing StateError: Bad state: Future already completed as an SDK-originated fatal event.

Changes:

Guard Completer completion in the web script DOM loader so subsequent terminal events are ignored.
Add browser regression tests covering load → error and error → load event delivery.
Add package:web/web.dart import to support DOM event dispatching in tests.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/flutter/lib/src/web/script_loader/web_script_dom_api.dart	Adds `isCompleted` guards around `onLoad`/`onError` handlers to prevent double completion.
packages/flutter/test/web/sentry_script_loader_test.dart	Adds Chrome/browser tests ensuring second terminal event dispatch does not throw and future settlement is stable.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Keep package:web usage in the existing browser test utility. Use the same DOM abstraction as neighboring script loader tests. Co-Authored-By: Codex <[email protected]>

Name the browser helper after the event it dispatches without implying script ordering. Co-Authored-By: Codex <[email protected]>

Cancel both DOM event subscriptions after the script load future settles. Release their callbacks and captured state. Co-Authored-By: Codex <[email protected]>

github-actions · 2026-07-21T09:28:13Z

Android Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	357.22 ms	346.12 ms	-11.10 ms
Size	14.55 MiB	15.87 MiB	1.31 MiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
`9993fa9`	389.44 ms	390.85 ms	1.41 ms
`c741aa5`	360.67 ms	367.86 ms	7.19 ms
`cdf371b`	367.64 ms	377.02 ms	9.38 ms
`ebccb5b`	363.79 ms	371.10 ms	7.31 ms
`6287dc4`	390.30 ms	399.12 ms	8.82 ms
`51520fc`	351.89 ms	349.79 ms	-2.10 ms
`3fe9e80`	362.67 ms	376.19 ms	13.52 ms
`d8f332d`	365.31 ms	349.98 ms	-15.33 ms
`819c1e7`	449.80 ms	442.98 ms	-6.82 ms
`29e8ebe`	389.91 ms	395.76 ms	5.84 ms

App size

Revision	Plain	With Sentry	Diff
`9993fa9`	14.55 MiB	15.87 MiB	1.31 MiB
`c741aa5`	14.55 MiB	15.87 MiB	1.31 MiB
`cdf371b`	13.93 MiB	15.18 MiB	1.25 MiB
`ebccb5b`	13.93 MiB	15.18 MiB	1.25 MiB
`6287dc4`	13.93 MiB	15.18 MiB	1.25 MiB
`51520fc`	13.93 MiB	15.18 MiB	1.25 MiB
`3fe9e80`	14.55 MiB	15.87 MiB	1.31 MiB
`d8f332d`	14.55 MiB	15.87 MiB	1.31 MiB
`819c1e7`	13.93 MiB	15.00 MiB	1.06 MiB
`29e8ebe`	13.93 MiB	15.06 MiB	1.13 MiB

github-actions · 2026-07-21T09:29:57Z

iOS Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1264.85 ms	1262.38 ms	-2.47 ms
Size	5.83 MiB	6.28 MiB	460.78 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
`af96ef2`	1260.79 ms	1259.61 ms	-1.17 ms
`b6c8720`	1252.65 ms	1266.61 ms	13.96 ms
`af4c7c1`	1246.85 ms	1255.35 ms	8.50 ms
`8af916c`	1246.66 ms	1240.79 ms	-5.87 ms
`d0aa4b6`	1268.23 ms	1268.39 ms	0.15 ms
`91629ec`	1257.91 ms	1255.93 ms	-1.98 ms
`c002f00`	1252.47 ms	1258.78 ms	6.31 ms
`a34fde0`	1255.35 ms	1254.31 ms	-1.03 ms
`3135a81`	1258.11 ms	1247.48 ms	-10.63 ms
`d5a1225`	1252.46 ms	1254.66 ms	2.20 ms

App size

Revision	Plain	With Sentry	Diff
`af96ef2`	5.53 MiB	6.02 MiB	501.31 KiB
`b6c8720`	7.86 MiB	9.44 MiB	1.58 MiB
`af4c7c1`	5.83 MiB	6.28 MiB	460.73 KiB
`8af916c`	5.73 MiB	6.18 MiB	463.84 KiB
`d0aa4b6`	5.53 MiB	6.02 MiB	502.04 KiB
`91629ec`	5.83 MiB	6.28 MiB	459.63 KiB
`c002f00`	5.65 MiB	6.09 MiB	448.38 KiB
`a34fde0`	5.66 MiB	6.10 MiB	451.57 KiB
`3135a81`	5.73 MiB	6.17 MiB	453.76 KiB
`d5a1225`	5.73 MiB	6.17 MiB	453.73 KiB

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit ab59bbb. Configure here.}

cursor · 2026-07-21T09:52:02Z

+      completer.completeError('Failed to load $src');
+      cancelSubscriptions();
+    }
+  });


Subscriptions leak on TT failure

Low Severity

Flagging per the Dart resource-disposal guidance in the review rules: load/error subscriptions are created before the Trusted Types try/catch, but cancelSubscriptions is not called when TrustedTypesException is thrown. The listener closures capture those subscriptions, so the unattached HTMLScriptElement can stay retained after policy creation fails.

Additional Locations (1)

packages/flutter/lib/src/web/script_loader/web_script_dom_api.dart#L17-L34

^{Triggered by project rule: PR Review Guidelines for Cursor Bot (Root)}

^{Reviewed by Cursor Bugbot for commit ab59bbb. Configure here.}

fix(flutter): Guard script completion

f0c4fb3

Ignore repeated load and error events after the web script loader. Prevent SDK-originated StateError events when browsers redeliver terminal script events. Fixes #3906 Co-Authored-By: Codex <[email protected]>

buenaflor marked this pull request as ready for review July 21, 2026 09:05

buenaflor requested a review from denrase as a code owner July 21, 2026 09:05

Copilot AI review requested due to automatic review settings July 21, 2026 09:05

Copilot started reviewing on behalf of buenaflor July 21, 2026 09:06 View session

Copilot AI reviewed Jul 21, 2026

View reviewed changes

test(flutter): Hide script DOM details

ab5123f

Keep package:web usage in the existing browser test utility. Use the same DOM abstraction as neighboring script loader tests. Co-Authored-By: Codex <[email protected]>

sentry Bot reviewed Jul 21, 2026

View reviewed changes

Comment thread packages/flutter/lib/src/web/script_loader/web_script_dom_api.dart Outdated

buenaflor and others added 2 commits July 21, 2026 11:15

test(flutter): Rename script event helper

5bccfcc

Name the browser helper after the event it dispatches without implying script ordering. Co-Authored-By: Codex <[email protected]>

fix(flutter): Cancel script subscriptions

f5a33d9

Cancel both DOM event subscriptions after the script load future settles. Release their callbacks and captured state. Co-Authored-By: Codex <[email protected]>

denrase approved these changes Jul 21, 2026

View reviewed changes

Merge branch 'main' into fix/web-script-double-completion

ab59bbb

buenaflor enabled auto-merge (squash) July 21, 2026 09:49

buenaflor merged commit f07030a into main Jul 21, 2026
67 of 69 checks passed

cursor Bot reviewed Jul 21, 2026

View reviewed changes

buenaflor deleted the fix/web-script-double-completion branch July 21, 2026 09:52

This was referenced Jul 21, 2026

publish: getsentry/[email protected] getsentry/publish#8946

Closed

publish: getsentry/[email protected] getsentry/publish#8947

Closed

github-actions Bot mentioned this pull request Jul 21, 2026

Web: loadScript double-completes its Completer — 'Bad state: Future already completed' reported as fatal #3906

Closed

Uh oh!

Uh oh!

Conversation

buenaflor commented Jul 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

📜 Description

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

Uh oh!

github-actions Bot commented Jul 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Semver Impact of This PR

Features

Fixes

Flutter

Other

Dependencies

Deps

Internal Changes

Uh oh!

codecov Bot commented Jul 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

github-actions Bot commented Jul 21, 2026

Android Performance metrics 🚀

Baseline results on branch: main

Startup times

App size

Uh oh!

github-actions Bot commented Jul 21, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

iOS Performance metrics 🚀

Baseline results on branch: main

Startup times

App size

Uh oh!

Uh oh!

cursor Bot left a comment

Choose a reason for hiding this comment

Uh oh!

cursor Bot Jul 21, 2026

Choose a reason for hiding this comment

Subscriptions leak on TT failure

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

buenaflor commented Jul 21, 2026 •

edited

Loading

github-actions Bot commented Jul 21, 2026 •

edited

Loading

codecov Bot commented Jul 21, 2026 •

edited

Loading

github-actions Bot commented Jul 21, 2026 •

edited

Loading