Error while applying timeScale options after enabling left and right scales

[timocov]

Lightweight Charts Version: dev version

Steps/code to reproduce:

A test case for applying options:

function generateBar(i, target) {
	var step = (i % 20) / 1000;
	var base = i / 5;
	target.open = base * (1 - step);
	target.high = base * (1 + 2 * step);
	target.low = base * (1 - 2 * step);
	target.close = base * (1 + step);
}

function generateData() {
	var res = [];
	var time = new Date(Date.UTC(2018, 0, 1, 0, 0, 0, 0));
	for (var i = 0; i < 500; ++i) {
		var item = {
			time: time.getTime() / 1000,
		};
		time.setUTCDate(time.getUTCDate() + 1);

		generateBar(i, item);
		res.push(item);
	}
	return res;
}

// eslint-disable-next-line no-unused-vars
function runTestCase(container) {
	var chart = LightweightCharts.createChart(container);

	var mainSeries = chart.addCandlestickSeries();

	mainSeries.setData(generateData());

	chart.applyOptions({
		leftPriceScale: { visible: true },
		rightPriceScale: { visible: true },
		timeScale: {}, // this cause an error
	});
}

Actual behavior:

A ton of errors like the following:

lightweight-charts.standalone.development.js:136 Uncaught Error: Value is null
    at ensureNotNull (lightweight-charts.standalone.development.js:136)
    at ChartWidget._private__adjustSizeImpl (lightweight-charts.standalone.development.js:10164)
    at ChartWidget.adjustSize (lightweight-charts.standalone.development.js:10059)
    at Object.callback (lightweight-charts.standalone.development.js:9989)
    at lightweight-charts.standalone.development.js:1560
    at Array.forEach (<anonymous>)
    at Delegate.fire (lightweight-charts.standalone.development.js:1560)
    at TimeScale.applyOptions (lightweight-charts.standalone.development.js:5881)
    at ChartModel.applyOptions (lightweight-charts.standalone.development.js:7237)
    at ChartWidget.applyOptions (lightweight-charts.standalone.development.js:10063)

Expected behavior:

No errors, both left and right price scales are visible.

The issue caused by #290.