TypeError instead of NotAllowedError in navigator.clipboard.write(image/png DOMString)

[karlcow]

wpt/clipboard-apis/async-navigator-clipboard-basics.https.html

Lines 156 to 160 in 92f1c29

	promise_test(async t => {
	await getPermissions();
	const item = new ClipboardItem({'image/png': 'not an image'});
	await promise_rejects_js(t, TypeError, navigator.clipboard.write([item]));
	}, 'navigator.clipboard.write(image/png DOMString) fails');

The current specificiation for write(data)
https://w3c.github.io/clipboard-apis/#dom-clipboard-write

In Steps 4, it says:

4. For each clipboardItem in dataList:

and then in 4.1.2.*

2. If representationDataPromise was rejected, then:
   1.Reject p with "NotAllowedError" DOMException in realm.
   2. Abort these steps.

Here the test is assessing a TypeError instead of NotAllowedError.
Is there another step I'm missing?

@saschanaz @whsieh