Crash with "Cannot read property 'constraint' of undefined" in latest Nightly

[zombie]

TypeScript Version: 2.9.0-dev.20180425

Code

Note: if the code doesn't make sense, that's because it's a reduced test case from Firefox source.

class SchemaAPIManager extends EventEmitter {
  _createExtGlobal() {
    let global = {};
    Object.assign(global, {
      extensions: this,
    });
  }
}

Trying to compile above using:

..\TypeScript\node_modules\.bin\tsc -t es6 sample.ts

Actual behavior:

TypeError: Cannot read property 'constraint' of undefined
    at getConstraintDeclaration (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:26581:76)
    at isTypeParameterWithKeyofConstraint (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:36496:45)
    at isLiteralOfContextualType (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:36510:28)
    at getWidenedLiteralLikeTypeForContextualType (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:30001:18)
    at checkExpressionForMutableLocation (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:36530:17)
    at checkPropertyAssignment (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:36536:20)
    at checkObjectLiteral (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:33125:58)
    at checkExpressionWorker (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:36632:28)
    at checkExpression (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:36584:42)
    at checkExpressionWithContextualType (D:\git\TypeScript\node_modules\typescript\lib\tsc.js:36449:26)

This doesn't seem to throw on previous stable version 2.8.

[zombie]

Also note that it doesn't throw without the ES6 target.

[weswigham]

Fixed by #23690 (we saw this in our RWC suite)

[weswigham]

@zombie do you still have this problem in the latest nightly? The patch should have been included in last night's build.

[zombie]

Yep, confirmed it works in 2.9.0-dev.20180430, thanks.