While writing a custom Class in Actionscript 3 today I came across an issue that took me a little bit to figure out where the compile error was coming from. I was getting the wonderful error:

After a bit of troubleshooting I discovered that a reference to the stage in my Class was returning null. I did some research and found that the stage is really a DisplayObject's reference to the stage DisplayObject.stage. However, if that DisplayObject is not yet added to the stage, the stage of the DisplayObject is not instantiated yet and returns a null value. In my case, the class was a Sprite I was adding to the stage at runtime.

I then discovered that my Class shouldn't get initialized until it was fully added to the stage since I had calls to the the stage class such as stage listeners and stage properties. I then determined that it was essential to add an event listener for my Sprite to be added to the stage:

Once the Object is added to the stage, you can initialize the rest of the Class. This was an easy fix to the issue that I hope others find useful.