Exception in getSpecialPropertyAssignmentKind when handling `||` in const value

[TysonAndre]

TypeScript Version: 2.4.0-dev.20170505 (nightly)

Code

// (Using react version "15.4.2")
// This is a .js file, using --checkJS (and extra lines were cut out)
define(function(require) {
    'use strict';

    const { Component} = require('react');

    const DEFAULT_MESSAGE = 'Uh-oh, something went wrong...';

    class Errors extends Component {
        _renderMessage(error) {
            const message = error.message || DEFAULT_MESSAGE;
        }
    }
});

# install tsc 20170505 and react 15.4.2 first
tsc --allowJs --checkJs --strict --noEmit example.js

Expected behavior:
Does not crash
Actual behavior:
Crashes because operatorToken is not an object, and the code is trying to access expr.operatorToken.kind

Additionally, with this patch to diagnose the cause, I saw more info

    function getSpecialPropertyAssignmentKind(expression) {
        if (!isInJavaScriptFile(expression)) {
            return 0;
        }     
        var expr = expression;
// begin patch
        if (!expr.operatorToken) {
            console.log('getSpecialPropertyAssignmentKind op', expr);  // This logged, for the '||' operator?
            return 0;
        }     
        if (!expr.left) {
            console.log('getSpecialPropertyAssignmentKind left', expr);
            return 0;
        } 
// end patch

Output: https://gist.github.com/TysonAndre/ba9ccf4ada6401d71f877c07f2700dfb

[mhegazy]

I am unable to reproduce the original issue, can you share more context..

c:\test\15616>type a.js
// (Using react version "15.4.2")
// This is a .js file, using --checkJS (and extra lines were cut out)
define(function(require) {
    'use strict';

    const { Component} = require('react');

    const DEFAULT_MESSAGE = 'Uh-oh, something went wrong...';

    class Errors extends Component {
        _renderMessage(error) {
            const message = error.message || DEFAULT_MESSAGE;
        }
    }
});

c:\test\15616>type jsconfig.json
{
    "compilerOptions": {
        "checkJs": true,
        "noEmit": true
    }
}

c:\test\15616>ls node_modules\@types
[.]         [..]        [react]     [requirejs]
               0 File(s)              0 bytes
               4 Dir(s)  40,390,402,048 bytes free

c:\test\15616>tsc --v
Version 2.3.2

c:\test\15616>tsc --p jsconfig.json

c:\test\15616>echo %ERRORLEVEL%
0

[TysonAndre]

1. Try the exact command I gave, without a jsConfig?
2. I stated I was using 2.4.0-dev in the ticket, you're using something different (I can reproduce in 2.4.0-dev-2017-05-05 but this isn't an issue in 2.3.2)

» tsc  --version                               
Version 2.4.0-dev.20170505
» tsc --allowJs --checkJs --strict --noEmit example.js

[mhegazy]

I see.. thanks looks like a regression from #15586. @sandersn can you take a look.

[chris-codaio]

Looks like this is blocking the start of our JS -> TS migration. Looking forward to a fix :)

[sandersn]

The better check is just whether the declaration is a BinaryExpression, since multiple kinds of Javascript declarations use assignment, and those are the only declarations whose kind is BinaryExpression.

#15594 has this fix too, but I'll give it its own PR to get it in faster.