An action script error occurred

Hi guys I've got sudden error

Code: [Select]

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at stencyl.api.engine.actor::Actor/die()[/home/stencyl/stencyl.net/jenkins/jobs/StencylWorks-Dist/workspace/plaf/flash/root/stencyl/api/engine/actor/Actor.as:2615]
at Function/<anonymous>()[/Users/Almakos/stencylworks/preview/scripts/Design_16_16_killbubble.as:58]
at stencyl.api.engine::TimedTask/update()[/home/stencyl/stencyl.net/jenkins/jobs/StencylWorks-Dist/workspace/plaf/flash/root/stencyl/api/engine/TimedTask.as:46]
at stencyl.api.engine::GameState/innerUpdate()[/home/stencyl/stencyl.net/jenkins/jobs/StencylWorks-Dist/workspace/plaf/flash/root/stencyl/api/engine/GameState.as:1661]
at stencyl.api.engine::GameState/postUpdate()[/home/stencyl/stencyl.net/jenkins/jobs/StencylWorks-Dist/workspace/plaf/flash/root/stencyl/api/engine/GameState.as:1511]
at stencyl.api.engine::GameState/update()[/home/stencyl/stencyl.net/jenkins/jobs/StencylWorks-Dist/workspace/plaf/flash/root/stencyl/api/engine/GameState.as:1493]
at org.flixel::FlxGame/update()[/home/stencyl/stencyl.net/jenkins/jobs/StencylWorks-Dist/workspace/plaf/flash/flixel/org/flixel/FlxGame.as:407]
Is it possible to say what the problem is according to error description?
Thanks

Try checking that "this Actor" is alive before killing it.

same error. If I keep pressing continue, error window will keep popping up infinite amount times.
Some times game will freeze without error window or any feedback

Nah, I mean put the "is alive" check just before killing the Actor -- so inside the "do after" block.

facepalm 

works well so far
Thank you