Merge pull request #346 from airbnb/btw/keypathwarning

Add log warning for missing keypath

lottie-ios/Classes/Private/LOTAnimationView.m

@@ -317,6 +317,8 @@
     [CATransaction setDisableActions:YES];
     [_compContainer displayWithFrame:_compContainer.currentFrame forceUpdate:YES];
     [CATransaction commit];
+  } else {
+    NSLog(@"%s: Keypath Not Found: %@", __PRETTY_FUNCTION__, keypath);
   }
 }