Missing namespace member warnings are the wrong way round

[Rich-Harris]

A situation like this...

// main.js
import * as foo from './foo.js';
console.log( foo.bar );

// foo.js
export const notBar = 42;

...results in a bundle like this...

const notBar = 42;

var foo = Object.freeze({
  notBar: notBar
});

console.log( foo.bar );

...and a warning like this:

Export 'bar' is not defined by 'main.js'

The warning is wrong – it's foo.js that should define bar, not main.js. If it was correct, the message would still be somewhat cryptic.

Also, there's really no need to reify the foo namespace in cases like this.