Strange error for JS enum with missing braces

[ghost]

TypeScript Version: 3.1.0-dev.20180830

Code

/** @enum number */
const E = { A: 0 };

Expected behavior:

Useful error message, perhaps '{' expected..

Actual behavior:

src/a.js:1:11 - error TS2693: 'number' only refers to a type, but is being used as a value here.

But the error isn't fixed if I define const number = 0;...