Merge pull request #1994 from NativeScript/raikov/fix-animations-crash

Fix animations crash

ui/animation/keyframe-animation.ts

@@ -105,8 +105,10 @@ export class KeyframeAnimation {
             this._isPlaying = false;
             for (let i = this._nativeAnimations.length - 1; i >= 0; i--) {
                 let animation = this._nativeAnimations[i];
+                if (animation.isPlaying) {
                     animation.cancel();
                 }
+            }
             this._rejectAnimationFinishedPromise();
         }
     }