The following code:

const controller = new AbortController();
const signal = controller.signal;
const response = await fetch('big.bin', { signal });
response.arrayBuffer().catch(e => console.log(e));
controller.abort();

Should log an AbortError DOMException. As currently implemented, it logs a TypeError instead.

This is tested in the wpt test external/wpt/fetch/api/abort/general.html which reports the following failures:

FAIL Fetch aborted & connection closed when aborted after calling response.arrayBuffer() assert_throws: function "function() { throw e }" threw object "TypeError: Failed to fetch" that is not a DOMException AbortError: property "code" is equal to undefined, expected 20
FAIL Fetch aborted & connection closed when aborted after calling response.blob() assert_throws: function "function() { throw e }" threw object "TypeError: Failed to fetch" that is not a DOMException AbortError: property "code" is equal to undefined, expected 20
FAIL Fetch aborted & connection closed when aborted after calling response.formData() assert_throws: function "function() { throw e }" threw object "TypeError: Failed to fetch" that is not a DOMException AbortError: property "code" is equal to undefined, expected 20
FAIL Fetch aborted & connection closed when aborted after calling response.json() assert_throws: function "function() { throw e }" threw object "TypeError: Failed to fetch" that is not a DOMException AbortError: property "code" is equal to undefined, expected 20
FAIL Fetch aborted & connection closed when aborted after calling response.text() assert_throws: function "function() { throw e }" threw object "TypeError: Failed to fetch" that is not a DOMException AbortError: property "code" is equal to undefined, expected 20

This is due to be fixed in the implementation of step 3 in https://docs.google.com/document/d/1OuoCG2uiijbAwbCw9jaS7tHEO0LBO_4gMNio1ox0qlY/edit#heading=h.fvc7d7q07oio ("Fetch API cancellation design doc" section "Body cancellation").