Error while closing tab pages: Could not find tab for <id>

[bsclifton]

• Did you search for similar issues before submitting this one?

• Describe the issue you encountered:
  When closing multiple tab pages by right clicking and picking Close tab page, the UI stops responding and the following error is written to stdout:

An uncaught exception occurred in the main process Uncaught Exception:
AssertionError: Could not find tab for 87
    at Object.getTabPropertyByTabId (/Users/clifton/Documents/browser-laptop/app/common/state/tabState.js:464:12)
    at Object.getWindowId (/Users/clifton/Documents/browser-laptop/app/common/state/tabState.js:470:21)
    at tabsReducer (/Users/clifton/Documents/browser-laptop/app/browser/reducers/tabsReducer.js:140:39)
    at reducers.reduce (/Users/clifton/Documents/browser-laptop/js/stores/appStore.js:380:24)
    at Array.reduce (<anonymous>)
    at applyReducers (/Users/clifton/Documents/browser-laptop/js/stores/appStore.js:378:68)
    at handleAppAction (/Users/clifton/Documents/browser-laptop/js/stores/appStore.js:420:14)
    at callbacks.forEach (/Users/clifton/Documents/browser-laptop/js/dispatcher/appDispatcher.js:85:7)
    at Array.forEach (<anonymous>)
    at AppDispatcher.dispatchToOwnRegisteredCallbacks (/Users/clifton/Documents/browser-laptop/js/dispatcher/appDispatcher.js:84:20)

• Platform (Win7, 8, 10? macOS? Linux distro?):
  macOS

• Brave Version (revision SHA):
  0.17.9

• Steps to reproduce:

  1. Set your tab page size to 20
  2. Open about:newtab
  3. Use middle click or cmd/ctrl + click to open about 5 or 6 tab pages worth of tabs. Open them as fast as you can.
  4. Start closing each tab page by right clicking the tab page and picking Close tab page

• Actual result:
  Occasionally (but not every time), I'll see the gigantic error logged above (could not find tab for 99 (or whatever the ID is)). Tab page doesn't close and UI seems to not respond anymore

• Expected result:
  Tab page should be closed.

• Will the steps above reproduce in a fresh profile? If not what other info can be added?

• Is this an issue in the currently released version?

• Can this issue be consistently reproduced?

• Extra QA steps:
  1.
  2.
  3.

• Screenshot if needed:

• Any related issues:

[luixxiul]

Another STR:

1. Clear the browser's profile
2. Start the browser
3. Open about:preferences in a new tab next to Welcome tab
4. Detach the preference tab
5. Re-attach the preference tab
6. Click the close button on the tab