JSONLoader: Fixed geometry.bones check.

src/loaders/JSONLoader.js

@@ -451,7 +451,7 @@ THREE.JSONLoader.prototype.parse = function ( json, texturePath ) {
 
 		geometry.bones = json.bones;
 
-		if ( geometry.bones.length > 0 && ( geometry.skinWeights.length !== geometry.skinIndices.length || geometry.skinIndices.length !== geometry.vertices.length ) ) {
+		if ( geometry.bones && geometry.bones.length > 0 && ( geometry.skinWeights.length !== geometry.skinIndices.length || geometry.skinIndices.length !== geometry.vertices.length ) ) {
 
 				console.warn( 'When skinning, number of vertices (' + geometry.vertices.length + '), skinIndices (' +
 					geometry.skinIndices.length + '), and skinWeights (' + geometry.skinWeights.length + ') should match.' );