fix bbox validation check in particle emitter

jme3-core/src/main/java/com/jme3/effect/ParticleEmitter.java

@@ -1124,7 +1124,7 @@ public class ParticleEmitter extends Geometry {
         lastPos.set(getWorldTranslation());
 
         //This check avoids a NaN bounds when all the particles are dead during the first update.
-        if (!min.equals(Vector3f.POSITIVE_INFINITY) && !max.equals(Vector3f.NEGATIVE_INFINITY)) {
+        if (Vector3f.isValidVector(min) && Vector3f.isValidVector(max)) {
             BoundingBox bbox = (BoundingBox) this.getMesh().getBound();
             bbox.setMinMax(min, max);
             this.setBoundRefresh();