Путь содержит недопустимые знаки.

в System.Security.Permissions.FileIOPermission.HasIllegalCharacters(String[] str)
в System.Security.Permissions.FileIOPermission.AddPathList(FileIOPermissionAccess access, AccessControlActions control, String[] pathListOrig, Boolean checkForDuplicates, Boolean needFullPath, Boolean copyPathList)
в System.Security.Permissions.FileIOPermission..ctor(FileIOPermissionAccess access, AccessControlActions control, String[] pathList, Boolean checkForDuplicates, Boolean needFullPath)
в System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy)
в System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options)
в System.IO.StreamWriter.CreateFile(String path, Boolean append)
в System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize)
в System.IO.StreamWriter..ctor(String path, Boolean append)
в PluginCore.Helpers.FileHelper.WriteFile(String file, String text, Encoding encoding, Boolean saveBOM)
в FlashDevelop.Docking.TabbedDocument.Save(String file)
в FlashDevelop.Docking.TabbedDocument.Save()
в FlashDevelop.MainForm.SaveAllModified(Object sender, EventArgs e)

package
{
package    
{
    import flash.display.Shape;
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.geom.Rectangle;
    import flash.events.MouseEvent;
       
    public class Main extends Sprite    
    {
     public function Main():void    
     {
      if (stage) init();
      else addEventListener(Event.ADDED_TO_STAGE, init);
     }
        
     private function init(e:Event = null):void    
     {
      removeEventListener(Event.ADDED_TO_STAGE, init);

      for (var i:int; i <= 10; i++)
      {
       var vrag:Enemy = new Enemy(Math.random()*600, Math.random()*600);   //Создание врага и добавление его на сцену
       addChild(vrag);    
      };
      stage.addEventListener(Event.ENTER_FRAME, vrag.moveEnemy);    
           
     }
        
    }
       
}

package     
{
    import flash.display.Shape;
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.geom.Rectangle;

    public class Enemy extends Sprite
    {

     public function Enemy(coord_x:int,coord_y:int)    
     {
      this.graphics.lineStyle(1);
      this.graphics.beginFill(0x00f3da, 1);
      this.graphics.drawCircle(coord_x, coord_y, 25);
      this.addEventListener(MouseEvent.CLICK, killEnemy);

     }
        
     //Функция уничтожения врага
     public function killEnemy(e:MouseEvent):void     
     {
      this.parent.removeChild(this);
     }
     //Функия движения врага
     public function moveEnemy(e:Event):void
     {
         this.parent.x += 0.5;
      this.parent.y += 0.5;
     }
        
    }

}

     this.parent.x += 0.5;
               this.parent.y += 0.5;

  this.x += 0.5;
               this.y += 0.5;