Logical nullish assignment (??=) throwing error

[sothix]

This code seems to be breaking latest NPM version: 2.13.1 with the following error:

let a = [1,2];
a[0] ??= 0;

Uncaught TypeError: Cannot read property 'paren' of undefined

[bespokebob]

I'm seeing this on just a regular nullish expression on both 2.13.0 and 2.13.1. The source line of the error is

jshint/src/jshint.js

Line 2453 in 11dc0a6

if (!right.paren && (right.id === "||" || right.id === "&&")) {

[jugglinmike]

A fix is under review here: gh-3563

JSHint does not currently support "logical assignment" operator nor will it following the acceptance of that patch. The bug in this case is the crash; JSHint is expected to report a syntax error for the provided input. Please refer to gh-3544 to follow the implementation of logical assignment.

[bespokebob]

I was seeing this in the codemirror editor, using the jshint integration, while typing a nullish coalescing expression. So it's probably the same issue - I was in the middle of typing an (incomplete) expression and jshint crashed instead of returning a syntax error for the incomplete line.