Resolve missing trap for failed deserialization in fetch transport

Author: kadamwhite

fetch/fetch-transport.js

@@ -122,6 +122,9 @@ const parseFetchResponse = ( response, wpreq ) => {
 		return response.json().then( ( err ) => {
 			// Throw the error object to permit proper error handling.
 			throw err;
+		}, () => {
+			// JSON serialization failed; throw the underlying response.
+			throw response;
 		} );
 	}
 

tests/integration/error-states.js

@@ -5,7 +5,7 @@ const SUCCESS = 'success';
 
 describe.each( [
 	[ 'wpapi/superagent', require( '../../superagent' ) ],
-	// [ 'wpapi/fetch', require( '../../fetch' ) ],
+	[ 'wpapi/fetch', require( '../../fetch' ) ],
 ] )( '%s: error states:', ( transportName, WPAPI ) => {
 
 	it( 'invalid root endpoint causes a transport-level 404 error', () => {