fetchurl thenresponse = const reader = responsebodygetReader; return new ReadableStream startcontroller function read

To handle errors in the above code, you can add a catch block after the then block, like this:

fetch(url) .then(response => { const reader = response.body.getReader(); return new ReadableStream({ start(controller) { function read() { reader.read().then(({done, value}) => { if (done) { controller.close(); return; } controller.enqueue(value); read(); }); } read(); }, }); }) .catch(error => { console.error(error); });

This catch block will catch any errors that occur during the fetch or stream creation process. You can then handle the error however you like - logging it to the console, displaying an error message to the user, etc.