That's a first. If it's that way before you open any game, you probably want to reinstall Stencyl. On the other hand, if the issue in your original project is the cause, you can delete the scene that caused the error and it might solve it.
Open Stencyl and go to Tools > View Folder > View Workspace Folder > Games
From there, go to your game's folder > scenes and remove 0.xml and 0.scn. Then open scenes.xml in the same folder (you can use notepad or notepad++) and remove the line containing your scene. According to your logs, it's a scene called level 1.
As far as I know, that will delete that scene from your game, and if it is the root cause of your issue, it might get back to normal.