My player keeps falling through the platform

just when i think ive got him to land correctly ontop of the platform i keep getting this darn error "TypeError: Error #1009: Cannot access a property or method of a null object reference.
   at com.stencyl.models::Actor/fillCollisionInfo()[C:/Program Files (x86)/Stencyl/plaf/haxe/lib/stencyl/1,00/com/stencyl/models/Actor.hx:4812]
   at com.stencyl.models::Actor/getAllCollisionInfo()[C:/Program Files (x86)/Stencyl/plaf/haxe/lib/stencyl/1,00/com/stencyl/models/Actor.hx:4603]
   at com.stencyl.models::Actor/moveActorBy()[C:/Program Files (x86)/Stencyl/plaf/haxe/lib/stencyl/1,00/com/stencyl/models/Actor.hx:4661]
   at com.stencyl.models::Actor/internalUpdate()[C:/Program Files (x86)/Stencyl/plaf/haxe/lib/stencyl/1,00/com/stencyl/models/Actor.hx:1562]
   at com.stencyl.models::Actor/innerUpdate()[C:/Program Files (x86)/Stencyl/plaf/haxe/lib/stencyl/1,00/com/stencyl/models/Actor.hx:1519]
   at com.stencyl::Engine/update()[C:/Program Files (x86)/Stencyl/plaf/haxe/lib/stencyl/1,00/com/stencyl/Engine.hx:2481]
   at com.stencyl::Engine/postUpdate()[C:/Program Files (x86)/Stencyl/plaf/haxe/lib/stencyl/1,00/com/stencyl/Engine.hx:2604]
   at com.stencyl::Engine/onUpdate()[C:/Program Files (x86)/Stencyl/plaf/haxe/lib/stencyl/1,00/com/stencyl/Engine.hx:2597]
"

here's a better updated screen shot

Seems I'm not the only one that just ran into this problem. Using build 8311, I decided to switch my game from box2d to simple physics, and my player would just suddenly start falling through the tiles, though not at first -- usually after a little while and I made him jump a couple times.  I fiddled around a bit (mostly changing player physics to Normal, testing, and then Simple, and testing), and finally got the following error:

From the Console:

Code: [Select]

Level:     INFO
When:      2015-05-08 19:16:02:679
From:      stencyl.sw.app.filewatcher.ExternalAppLauncher

[Flash] Universal#uncaughtErrorHandler(51): Error #1009: Cannot access a property or method of a null object reference.
From the Flash Player error window:

Code: [Select]

An ActionScript error has occurred:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at MethodInfo-6037()[Source/scripts/Design_10_10_PlayerCollisions.hx:101]
at com.stencyl.behavior::TimedTask/update()[/usr/share/Stencyl-64/plaf/haxe/lib/stencyl/1,00/com/stencyl/behavior/TimedTask.hx:48]
at com.stencyl::Engine/update()[/usr/share/Stencyl-64/plaf/haxe/lib/stencyl/1,00/com/stencyl/Engine.hx:2340]
at com.stencyl::Engine/postUpdate()[/usr/share/Stencyl-64/plaf/haxe/lib/stencyl/1,00/com/stencyl/Engine.hx:2584]
at com.stencyl::Engine/onUpdate()[/usr/share/Stencyl-64/plaf/haxe/lib/stencyl/1,00/com/stencyl/Engine.hx:2577]

Any update on this? I'll probably try an updated version and see if the error is gone.