ofn-bend-path error / help?

[Ofnuts]

Agreeing with Krikor, you likely have a 3rd stroke somewhere, possibly a stray anchor.

Caveats:

• ofn-bend-path only alters the path vertically (given the shape you seem to want to wrap it around a half circle). 
  
• the ends of the "top" path being below the end of the "bottom" path may confuse the script as to which stroke is "top" and which is "bottom"