Does this support multiple cuts to a video?

[p45mark]

I'm trying to remove multiple sections from a video file and return output.mp4 but I keep getting errors when trying to read the output.mp4 file.

Is that possible with ffmpeg.wasm, and if so can someone point me in the right direction? I took the command from this SO post and tried to apply it to the ffmpeg.run() function. Running this locally with the ffmpeg cli works, but it's also incredibly slow so if there's a faster approach I'd also appreciate a recommendation for that.

ffmpeg.FS('writeFile', 'myFile.mp4', await fetchFile(url))
await ffmpeg.run('-i', 'myFile.mp4', '-vf', "select='between(t,4,6.5)+between(t,10,11)', setpts=N/FRAME_RATE/TB", 'output.mp4');
const data = ffmpeg.FS('readFile', 'output.mp4') // error here

but it throws one of these errors:

Uncaught RuntimeError: abort(OOM). Build with -s ASSERTIONS=1 for more info.
// or 
Error: ffmpeg.FS('readFile', 'output.mp4') error. Check if the path exists

As a sanity check to narrow these errors down to the cmds I'm passing to the run() function, this command does trim the video (removes footage from the start and end of the video so output.mp4 is a 3s long video)

await ffmpeg.run('-i', 'myFile.mp4', '-ss', '00:00:01.000', '-to', '00:00:04.000', '-codec', 'copy', 'output.mp4')

[p45mark]

If I run this cmd locally with the ffmpeg cli, it takes around 15s to complete with a 3min mp4. If I debug the async call to ffmpeg.run in my Javascript, it doesn't wait for the run command to complete.

Am I just missing some callback or something? Shouldn't it await for the cmd to finish or am I missing something in my run arguments to tell it to wait?