No type-checking for @property with misspelled type across files

TypeScript Version: 3.9.0-dev.20200225

Code

a.js

/**
 * @typedef MyType
 * @property {sting} [x]
 */

/** @param {MyType} p  */
export function f(p) {}

b.js

import {f} from "./a.js"
f({ x: 42 })

Expected behavior:

Error at sting.

Actual behavior:

No error.
There is an error if we call f({ x: 42 }) in a.js.

[DanielRosenwasser]

I'm not seeing this locally - do you have a repro? Is a.js actually being type-checked?

I'm testing this in a directory with only 3 files -- a.js and b.js as above and this tsconfig.json:

{
	"compilerOptions": {
		"allowJs": true,
		"checkJs": true,
		"noEmit": true,
	}
}

I can verify that a.js is being type-checked by adding this at the bottom:

/** @type {numbr} */
const x = 3

which correctly produces an error.

I'm also seeing an interesting effect in the editor -- when I make a whitespace change to b.js and go back to a.js the error appears, but when I make another (whitespace) change to a.js the error disappears. But running tsc at the command line I never see an error.