fromJSON does not work with LSTM

I’m trying to use a LSTM network to just feed messages from a discord server, as a fun experiment to see what it can come up with. The problem is when I save the data using toJSON and then restoring it, it seems like the data is incompatible with what fromJSON expects.

const network = new brain.recurrent.LSTM();
const data = await getDataSomehow()

network.fromJSON(data)

getDataSomehow loads the json file, parses it and returns the object. After doing this, this error is put in console whenever run is called:

Furthermore, when I try training with new data, if it encounters a character that was not in the original training data, it gives me Unrecognized character.

What am I doing wrong?

[robertleeplummerjr]

Reproduced. Great find @felangel and everyone who worked on this. Merging now, and will have a new version out within the next 10 minutes.

[jorgelahoz]

The same here, the issue appears when exportinf/importing to/from JSON. For example:

const BrainJS = require("brain.js");
var net = new BrainJS.recurrent.LSTM();
var trainOps = {
    iterations: 20000,
    errorThresh: 0.011,
    log: true,
    logPeriod: 1,
    timeout: Infinity     // the max number of milliseconds to train for --> number greater than 0
};
var data = [
    'doe, a deer, a female deer',
    'ray, a drop of golden sun',
    'me, a name I call myself',
];
net.train(data, trainOps);
var output = net.run('doe');  // ', a deer, a female deer'
console.log(output);
var json = net.toJSON();
net.fromJSON(json);
var output = net.run('doe');  // ', a deer, a female deer'
console.log(output);

Returns

Cannot read property 'length' of undefined
TypeError: Cannot read property 'length' of undefined
    at LSTM.run (/code/node_modules/brain.js/src/recurrent/rnn.js:311:27)