TypeError: Cannot read property 'precision' of undefined

[donmahallem]

If the provided JPEG has no SOF marker before the SOS marker the decode will crash line https://github.com/eugeneware/jpeg-js/blob/d340c1b2113328bdea955706e7c5f0bf0cad143b/lib/decoder.js#L97 as the frame is undefined.

To reproduce:

const jpeg = require("jpeg-js");
const buf = new Buffer("ffd8ffffffda", "hex");
jpeg.decode(buf);

I would help out with an PR but I am not sure where to implement the check and how extensive it should be as for example the SOI marker should appear before all the above or if just check if frame is defined inside the SOS handler.