chart-fx Fix endless update loop in the presence of empty DataSet

Describe the bug Empty DataSet causes some kind of endless update loop somewhere.

To Reproduce Create chart, add two empty datasets. Wait a second (to let JFX thread do pending tasks). After a second add a point to one of the datasets.

My reproducer in Kotlin

    val chart = frame("ChartFx", 1366.0 * 0.7, 768.0) {
        val xAxis = DefaultNumericAxis("x")
        val yAxis = DefaultNumericAxis("y")
        XYChart(xAxis, yAxis)
    }

    val first = DoubleDataSet("First")
    val second = DoubleDataSet("Second")

    withContext(Dispatchers.JavaFx) {
        chart.datasets.addAll(first, second)
    }

    delay(1000)
    first.add(150.0, 25.0)

Observed behavior High CPU and GPU usage, exceptions like

java.util.concurrent.RejectedExecutionException: Task com.sun.javafx.tk.quantum.PaintRenderJob@3195e9e1[Not completed, task = java.util.concurrent.Executors$RunnableAdapter@75ae38c1[Wrapped task = com.sun.javafx.tk.quantum.PresentingPainter@1ed15372]] rejected from com.sun.javafx.tk.quantum.QuantumRenderer@643b1d11[Terminated, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 4074]
	at java.base/java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2081)
	at java.base/java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:841)

when trying to exit application. Also endless loop (and the fix) was confirmed by a println statement inside updateAxisRange function. The problem goes away as soon as a point added to the second empty dataset.

Fix Suggested simple fix solves the problem.