Source text or Artwork?

This one seems new. I have a few scripts that work on the current document in SD. When I try to get source text it generates an appleScript error:::::–

tell application "Script Debugger"
      set scriptFullText to source text of current document
   on error errMsg number errNum
      return {errMsg, errNum} as text
   end try
end tell
--Script Debugger got an error: Can’t get artwork.-1728

I have other ways of doing this, but it seems like this is something that worked before but doesn’t.

Plus: “Artwork”

–> Script Debugger 7.0.11 (7A110)
–> Mac OS 10.11.6 (15G22010)

current document is a property of the script window class, so throwing an error is correct in this case. When I try your code, I get: “Script Debugger got an error: Can’t get current document.-1728”.