TextEncoder in libdef but cannot be used, even though TextEncoder can be

[wchargin]

Flow version: 0.145.0

Steps to reproduce

Brand new Yarn package with only flow-bin installed. In index.js:

// @flow
const util = require("util");
console.log(util.TextDecoder);
console.log(util.TextEncoder);

This is a straightforward use of the Node APIs, and works:

$ node index.js
[Function: TextDecoder]
[Function: TextEncoder]

Expected behavior

It should type-check.

Actual behavior

$ yarn flow --message-width 80
yarn run v1.22.10
$ /tmp/tmp.fTIX2thXuc/node_modules/.bin/flow --message-width 80
Error ┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈ index.js:4:18

Cannot get util.TextEncoder because property TextEncoder (did you mean
TextDecoder?) is missing in module util [1]. [prop-missing]

     index.js
        1│ // @flow
        2│ const util = require("util");
        3│ console.log(util.TextDecoder);
        4│ console.log(util.TextEncoder);
        5│

     ../flow/flowlib_812ef1ce4cab4593_1000/node.js
 [1] 2262│ declare module "util" {
     2263│   declare function debuglog(section: string): (data: any, ...args: any) => void;
     2264│   declare function format(format: string, ...placeholders: any): string;
     2265│   declare function log(string: string): void;
     2266│   declare function inspect(object: any, options?: util$InspectOptions): string;
     2267│   declare function isArray(object: any): boolean;
     2268│   declare function isRegExp(object: any): boolean;
     2269│   declare function isDate(object: any): boolean;
     2270│   declare function isError(object: any): boolean;
     2271│   declare function inherits(constructor: Function, superConstructor: Function): void;
     2272│   declare function deprecate(f: Function, string: string): Function;
     2273│   declare function promisify(f: Function): Function;
     2274│   declare function callbackify(f: Function): Function;
     2275│
     2276│   declare class TextDecoder {
     2277│     constructor(encoding?: string, options: {
     2278│       fatal?: boolean,
     2279│       ignoreBOM?: boolean,
     2280│       ...
     2281│     }): void;
     2282│     decode(input?: ArrayBuffer | DataView | $TypedArray, options?: { stream?: boolean, ... }): string;
     2283│     encoding: string;
     2284│     fatal: boolean;
     2285│     ignoreBOM: boolean;
     2286│   }
     2287│
     2288│   declare class TextEncoder {
     2289│     constructor(): void;
     2290│     encode(input?: string): Uint8Array;
     2291│     encoding: string;
     2292│   }
     2293│ }



Found 1 error
error Command failed with exit code 2.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Note that TextEncoder is declared, right after TextDecoder, as is
visible in the error trace. Both were added in #7713, first released in
v0.101.0; I can reproduce at that Flow version, too (and at v0.100.0 it
complains on both of them, as expected).

Can repro on Node 10 and Node 14.

Cannot repro on Flow Try (no such module util).

h/t @topocount for raising this issue

[noppa]

I'm guessing this is somehow because TextEncoder is also defined as a global type in streams.js libdef, whereas TextDecoder is not.