Line by line translation of thisismypassword's Picotron pxu decoder from python to typescript

pxu.ts

class CursorView {
    private data: DataView
    private cursor: number = 0

    constructor(data: DataView) {
        this.data = data;
    }

    getUint8() { return this.data.getUint8((this.cursor += 1) - 1); }
    getUint16() { return this.data.getUint16((this.cursor += 2) - 2, true); }
    getUint32() { return this.data.getUint32((this.cursor += 4) - 4, true); }
}

export function pxuDecode(encoded: Uint8Array): Uint8Array {
    const view = new CursorView(new DataView(encoded.buffer));
    const flags = view.getUint16();
    if ((flags & ~0x840) !== 0x2003) {
        throw new Error("Unknown flags");
    }
    const hasHeight = (flags & 0x40) !== 0;
    const longSize = (flags & 0x800) !== 0;
    const width = longSize ? view.getUint32() : view.getUint8();
    const height = hasHeight ? (longSize ? view.getUint32() : view.getUint8()) : 1;
    const size = width * height
    const bits = view.getUint8();
    if (bits !== 4) {
        throw new Error("Unknown bits division");
    }
    const data: number[] = [];
    const meanings: number[] = new Array(0xf).fill(null);
    let nextRepeat = 0xe;
    while (data.length < size) {
        const byte = view.getUint8();
        let value = byte & 0xf;
        if (value === 0xf) {
            value = view.getUint8();
            if (nextRepeat >= 0) {
                meanings[nextRepeat] = value;
            }
        } else {
            if (value === nextRepeat) {
                nextRepeat -= 1;
                while (nextRepeat >= 0 && meanings[nextRepeat] != null) {
                    nextRepeat -= 1;
                }
            }
            if (meanings[value] !== null) {
                value = meanings[value]
            } else {
                meanings[value] = value;
            }
        }
        let count = 1 + (byte >> 4);
        if (count == 0x10) {
            while (true) {
                const c = view.getUint8();
                count += c;
                if (c != 0xff) {
                    break;
                }
            }
        }
        for (let i = 0; i < count; i++) {
            data.push(value);
        }
    }
    return Uint8Array.from(data);
}

FYI, the code this was based on wasn't tested sufficiently well and was wrong for larger pxus
I've figured out the correct algorithm now (python version will end up in the shrinko repo soon)