Reset elector when a duplicate leader is detected and capture errors in Sentry

[bjester]

Summary

Background

• When a user opens more than one Studio tab, we have leader election logic which determines the browser tab that will be the lead for syncing all the tabs' changes to the backend
• According to the documentation for the library broadcast-channel that we use for leader election:

  Duplicate leadership can happen on rare occurences like when the CPU is on 100% for longer time, or the browser has throttled the javascript timers.

• On a Windows machine, with lower hardware specifications, Studio may run into situations where 'duplicate leadership' is detected, causing an error in that logic that attempts to restart the leader election. In this situation, it's possible that no leader could be elected and the frontend will stop syncing

Description of the change(s) you made

• Manually resets the channel._leaderElector value to allow restarting leader election, prevented by the error BroadcastChannel already has a leader-elector that is thrown in its presence
• Adds handling to capture related errors in Sentry since the error the user experienced wasn't logged to Sentry

Manual verification steps performed

1. To reproduce this issue, use a virtualbox VM with:

• Windows 10 OS
• 1 CPU
• 4096 MB of memory
• Firefox 108

2. Open a Studio channel in Firefox
3. Open the developer console
4. Right-click on the Firefox tab, and select 'Duplicate this tab'
5. Open the developer console on the duplicate tab
6. Refresh either tab until the leader election error appears, if it hasn't already

---

References

Resolves #3906

Comments

---

Contributor's Checklist

PR process:

• If this is an important user-facing change, PR or related issue the CHANGELOG label been added to this PR. Note: items with this label will be added to the CHANGELOG at a later time
• If this includes an internal dependency change, a link to the diff is provided
• The docs label has been added if this introduces a change that needs to be updated in the user docs?
• If any Python requirements have changed, the updated requirements.txt files also included in this PR
• Opportunities for using Google Analytics here are noted
• Migrations are safe for a large db

Studio-specifc:

• All user-facing strings are translated properly
• The notranslate class been added to elements that shouldn't be translated by Google Chrome's automatic translation feature (e.g. icons, user-generated text)
• All UI components are LTR and RTL compliant
• Views are organized into pages, components, and layouts directories as described in the docs
• Users' storage used is recalculated properly on any changes to main tree files
• If there new ways this uses user data that needs to be factored into our Privacy Policy, it has been noted.

Testing:

• Code is clean and well-commented
• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Any new interactions have been added to the QA Sheet
• Critical and brittle code paths are covered by unit tests

---

Reviewer's Checklist

This section is for reviewers to fill out.

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md