const stackVideos = useCallback(
    async (video1) => {
      try {
        console.log("Fetching video2 from storage...");
        const video2Ref = ref(storage, "video2.mp4");
        const video2Url = await getDownloadURL(video2Ref);
        const video2Blob = await (await fetch(video2Url)).blob();

        console.log("Writing video1 to FFmpeg FS...");
        await ffmpeg.FS("writeFile", "video1.mp4", await fetchFile(video1));

        console.log("Writing video2 to FFmpeg FS...");
        await ffmpeg.FS("writeFile", "video2.mp4", await fetchFile(video2Blob));

        console.log("Files in FFmpeg FS after write:");
        const files = await ffmpeg.FS("readdir", "/");
        console.log(files);

        const { start, end } = inputs[0];
        const startSeconds = new Date(`1970-01-01T${start}Z`).getTime() / 1000;
        const endSeconds = new Date(`1970-01-01T${end}Z`).getTime() / 1000;
        const duration = endSeconds - startSeconds;

        console.log("Running FFmpeg command...");
        await ffmpeg.run(
          "-i",
          "video1.mp4",
          "-ss",
          startSeconds.toString(),
          "-t",
          duration.toString(),
          "-i",
          "video2.mp4",
          "-filter_complex",
          "[0:v]scale=1080:-1[v1];[1:v]scale=-1:1920/2[v2scaled];[v2scaled]crop=1080:1920/2[v2cropped];[v1][v2cropped]vstack=inputs=2,scale=1080:1920[vid]",
          "-map",
          "[vid]",
          "-map",
          "0:a",
          "-c:v",
          "libx264",
          "-crf",
          "23",
          "-preset",
          "veryfast",
          "-shortest",
          "output1.mp4"
        );

        console.log("Files in FFmpeg FS after run:");
        const filesAfterRun = await ffmpeg.FS("readdir", "/");
        console.log(filesAfterRun);

        console.log("Reading output1.mp4 from FFmpeg FS...");
        const data = await ffmpeg.FS("readfile", "output1.mp4");
        console.log("after the FS readfile");
        const url = URL.createObjectURL(
          new Blob([data.buffer], { type: "video/mp4" })
        );
        setStackedVideo(url);
        setOutputFileReady(true); // Mark output file as ready
      } catch (err) {
        console.error("FFmpeg error output:", err);
        setError(`FFmpeg run error: ${err.message}`);
        setIsProcessing(false);
      }
    },
    [inputs]
  );

My error seems to be stemming from this line:

 const data = await ffmpeg.FS("readfile", "output1.mp4");

Seeing the ffmpeg.wasm documentation i thought the functions for some of the functions had changed, but when I changed it, it seemed like they did not recognise the new functions. Sometimes this will also give me some other errors like worker.js which I dont understand enough to debug this myself.

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