So I researched the issue further;
This is the javascript attempting to close the shape. However the auto generated experiment js has the line closeShape: false, which apparently it is not respecting.
Ultimately my issue is a duplicate of the issue from here in '19 - Drawing using the mouse as a brush - #6 by smweis
Here Jon’s answer is marked as a solution! My question is how do i implement this solution? ShapeStim.js is inside the local PsychoPy package, so how do i change @param {boolean} [options.closeShape= false] from the irksome true?