ofn-bend-path error / help?

[rich2005]

A different approach, might come in useful. 
This using only paths and Ottia Tuota's Path Transforms plugin see: https://www.gimp-forum.net/Thread-Path-transformations

Using this:

   

The plugin dialogue: Path shaped by a bezier arc

   

Gives this:

   

Remember, that arc is a 2-node path, no use making from a circular selection.