Nullish coalescing doesn't work as expected in TypeScript

Summary

Nullish coalescing doesn’t work as expected in TypeScript.

Steps To Reproduce:

1. Write this bit of code in a TypeScript (.ts) file const hello = 'hi' ?? 'test'
2. Add odd spacing for Prettier to fix
3. Run the formatting shortcut in VS Code

Expected result

The badly formatted code should get formatted by Prettier.

Actual result

Nothing happens, the spacing stays odd and the Prettier plugin thinks there’s a syntax error. See the log below.

Additional information

Formatting nullish coalescing operators still seems to work perfectly in JavaScript files (.js), so this is only an issue with TS.

This issue has been found to not be an issue with Prettier itself but with this extension specifically: https://github.com/prettier/prettier/issues/7428#issuecomment-589012567

VS Code Version: 1.44.0

Prettier Extension Version: 4.2.0

OS and version: Windows 10 - Version 10.0.18363 Build 18363

Prettier Log Output

["ERROR" - 00:02:14] Error formatting document.
["ERROR" - 00:02:14] Expression expected. (1:29)
> 1 |         const hello = 'hi' ?? 'test'
    |                             ^
SyntaxError: Expression expected. (1:29)
> 1 |         const hello = 'hi' ?? 'test'
    |                             ^
	at e (c:\projects\DFE\node_modules\prettier\parser-typescript.js:1:329)
	at Object.parse (c:\projects\DFE\node_modules\prettier\parser-typescript.js:1:2261773)
	at Object.parse$2 [as parse] (c:\projects\DFE\node_modules\prettier\index.js:10629:19)
	at coreFormat (c:\projects\DFE\node_modules\prettier\index.js:13888:23)
	at format (c:\projects\DFE\node_modules\prettier\index.js:14146:73)
	at formatWithCursor (c:\projects\DFE\node_modules\prettier\index.js:14162:12)
	at c:\projects\DFE\node_modules\prettier\index.js:42756:15
	at Object.format (c:\projects\DFE\node_modules\prettier\index.js:42775:12)
	at c:\Users\Admin\.vscode\extensions\esbenp.prettier-vscode-4.2.0\dist\extension.js:1:250598
	at t.default.safeExecution (c:\Users\Admin\.vscode\extensions\esbenp.prettier-vscode-4.2.0\dist\extension.js:1:250898)
	at t.default.<anonymous> (c:\Users\Admin\.vscode\extensions\esbenp.prettier-vscode-4.2.0\dist\extension.js:1:250578)
	at Generator.next (<anonymous>)
	at s (c:\Users\Admin\.vscode\extensions\esbenp.prettier-vscode-4.2.0\dist\extension.js:1:244725)

[Arrow7000]

Hm you’re right, this issue only happens in one of my repos but not in another.

I was finally able to work out what was causing the issue. react-slick, a dependency I was using, had prettier as a dependency for some reason. It was using an old version of prettier and apparently VS Code prefers using the local version of prettier if there is one rather than the version that comes installed with the plugin.

Installing the latest prettier as a direct dependency solved this.

[creambyemute]

@Arrow7000 You are my hero 🥳