Crash on poly move and sew inside custom context. Cannot figure this one out

[Benjam901]

Hello all,

I have been digging into the API and am writing a tool that is going to move and sew your UVs as you run along the polygons with your mouse.

The script so far is almost there as a first draft base functionality but when I move and sew the poly edges Maya crashes every time. Using the cmds command standalone is totally fine but when I run the command inside my custom context it kills it.

I can select each edge fine if I want to and select each face etc. is no problem, but move and sew is killing it every time. Perhaps I need to perform the operation on a more specific data set inside the model? 

Any tips I would greatly appreciate

gist:

https://gist.github.com/ben-hearn-sb/907a8d6647392794e48c026917e6267e

Cheers,

Ben