NPE in FbxLayerElement.fromElement()

[stephengold]

I'm testing current "master" branch with FBX assets downloaded from CGtrader, Mixamo, and Sketchfab.
Attempting to import certain FBX files causes the following crash:

Jan 28, 2023 11:10:18 PM com.jme3.app.LegacyApplication handleError
SEVERE: Uncaught exception thrown in Thread[jME3 Main,5,main]
java.lang.NullPointerException: Cannot read the array length because "layerElement.dataIndices" is null
	at com.jme3.scene.plugins.fbx.mesh.FbxLayerElement.fromElement(FbxLayerElement.java:202)
	at com.jme3.scene.plugins.fbx.mesh.FbxMesh.fromElement(FbxMesh.java:91)
	at com.jme3.scene.plugins.fbx.obj.FbxObjectFactory.createObject(FbxObjectFactory.java:192)
	at com.jme3.scene.plugins.fbx.FbxLoader.loadObjects(FbxLoader.java:195)
	at com.jme3.scene.plugins.fbx.FbxLoader.loadData(FbxLoader.java:161)
	at com.jme3.scene.plugins.fbx.FbxLoader.load(FbxLoader.java:110)
	at com.jme3.asset.DesktopAssetManager.loadLocatedAsset(DesktopAssetManager.java:272)
	at com.jme3.asset.DesktopAssetManager.loadAsset(DesktopAssetManager.java:388)
	at com.jme3.asset.DesktopAssetManager.loadModel(DesktopAssetManager.java:439)
	at com.jme3.asset.DesktopAssetManager.loadModel(DesktopAssetManager.java:444)
	at jme3test.helloworld.HelloJME3.loadModel(HelloJME3.java:88)
	at jme3test.helloworld.HelloJME3.simpleInitApp(HelloJME3.java:67)
	at com.jme3.app.SimpleApplication.initialize(SimpleApplication.java:240)
	at com.jme3.system.lwjgl.LwjglAbstractDisplay.initInThread(LwjglAbstractDisplay.java:139)
	at com.jme3.system.lwjgl.LwjglAbstractDisplay.run(LwjglAbstractDisplay.java:221)
	at java.base/java.lang.Thread.run(Thread.java:833)

The comment at FbxLayerElement.java:200 indicates that the intent was to copy dataIndices to data.
If dataIndices is null,the entire block should probably be skipped.

jmonkeyengine/jme3-plugins/src/fbx/java/com/jme3/scene/plugins/fbx/mesh/FbxLayerElement.java

Lines 199 to 207 in 7a5d085

	if (layerElement.data == null) {
	// For Smoothing / Materials, data = dataIndices
	layerElement.refInfoType = ReferenceInformationType.Direct;
	layerElement.data = new Integer[layerElement.dataIndices.length];
	for (int i = 0; i < layerElement.data.length; i++) {
	layerElement.data[i] = layerElement.dataIndices[i];
	}
	layerElement.dataIndices = null;
	}