Fix a rare NPE race condition in TransformKeyframeAnimation (#1955)

Fixes #1945
diff --git a/lottie/src/main/java/com/airbnb/lottie/animation/keyframe/TransformKeyframeAnimation.java b/lottie/src/main/java/com/airbnb/lottie/animation/keyframe/TransformKeyframeAnimation.java
index 5453d7b..fcab96c 100644
--- a/lottie/src/main/java/com/airbnb/lottie/animation/keyframe/TransformKeyframeAnimation.java
+++ b/lottie/src/main/java/com/airbnb/lottie/animation/keyframe/TransformKeyframeAnimation.java
@@ -169,7 +169,7 @@
     BaseKeyframeAnimation<?, PointF> position = this.position;
     if (position != null) {
       PointF positionValue = position.getValue();
-      if (positionValue.x != 0 || positionValue.y != 0) {
+      if (positionValue != null && (positionValue.x != 0 || positionValue.y != 0)) {
         matrix.preTranslate(positionValue.x, positionValue.y);
       }
     }