Error if the left operand of ?? is syntactically provable to not be nullish

[RyanCavanaugh]

Follow-on to #59003 based on a hit that PR had

[RyanCavanaugh]

@typescript-bot test top400

[typescript-bot]

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
test top400	✅ Started	👀 Results

[typescript-bot]

@RyanCavanaugh Here are the results of running the top 400 repos with tsc comparing main and refs/pull/59038/merge:

Something interesting changed - please have a look.

Details

ChatGPTNextWeb/ChatGPT-Next-Web

tsconfig.json

• error TS2869: Left operand of ?? is never undefined/null. Are you missing parentheses?
  • app/store/chat.ts#L600

microsoft/vscode

4 of 54 projects failed to build with the old tsc and were ignored

src/tsconfig.tsec.json

• error TS2869: Left operand of ?? is never undefined/null. Are you missing parentheses?
  • src/vs/workbench/contrib/testing/browser/testingExplorerView.ts#L138

src/tsconfig.json

• error TS2869: Left operand of ?? is never undefined/null. Are you missing parentheses?
  • src/vs/workbench/contrib/testing/browser/testingExplorerView.ts#L138

supabase/supabase

31 of 37 projects failed to build with the old tsc and were ignored

apps/studio/tsconfig.json

• error TS2869: Left operand of ?? is never undefined/null. Are you missing parentheses?
  • apps/studio/components/ui/ProjectUpgradeFailedBanner.tsx#L20

tailwindlabs/headlessui

1 of 5 projects failed to build with the old tsc and were ignored

packages/@headlessui-react/tsconfig.json

• error TS2869: Left operand of ?? is never undefined/null. Are you missing parentheses?
  • packages/@headlessui-react/src/utils/bugs.ts#L13

[RyanCavanaugh]

headlessui. Huh?

let isParentDisabled = parent?.getAttribute('disabled') === '' ?? false

supabase. Again, huh?

  const isAcknowledged =
    typeof window !== 'undefined' ? localStorage?.getItem(key) === 'true' ?? false : false

vscode. Looks like missing parens?

    return this.viewModel?.welcomeExperience === WelcomeExperience.ForWorkspace ?? true;

ChatGPT-Next-Web. Missing parens as found in prior PR

    if (historyMsgLength > modelConfig?.max_tokens ?? 4000)